During the past week, we’ve been on a road trip seeking to score a hat trick—records of three particular species of flying creatures best found in our vicinity on the Atlantic Coastal Plain of the Delmarva Peninsula. Our excursion led us to the seaside environs of Cape Henlopen State Park at the mouth of Delaware Bay.

So just what were these three species we so eagerly sought?

Were they the three gulls we found scavenging the beaches and marshes for the remains of some expired mollusk, crustacean, or fish?

Always fun to watch, but no, they weren’t the reason for our visit.

How about the four heron and egret species observed in the tidal marsh and at the park’s Gordon’s Pond; that’s even better than a hat trick, right?

Not bad, but nope, it wasn’t the herons and egrets.

Well, then it must be the shorebirds; yeah, it has got to be the shorebirds?

Left to right, a Willet (Tringa semipalmata), a Lesser Yellowlegs, and two Greater Yellowlegs.

Very nice, but it wasn’t the shorebirds either.

What about the three appearances of the Clapper Rail in the tidal marsh?

Now we’re reaching. No, it wasn’t the Clapper Rail’s numerous appearances.

The term “hat trick” has its origins in the game of cricket. A hurler upon retiring three batsmen with three consecutive balls was gifted a new hat. The three species we were seeking are, coincidentally, related to the insects called crickets. Our true goal was to track down the three species of annual cicadas known to emerge, sing, and breed during the late summer on the Atlantic Coastal Plain. None of these species are known to breed in the lower Susquehanna valley, but all are potential vagrants. We were quite fortunate to find all three singing in the vicinity of our temporary susquehannawildlife.net headquarters. During our numerous forays in the area, we were able to obtain sound and image records of two. To our disappointment though, the Northern Dusk-singing Cicada (Megatibicen grossus), a species nearing the end of its summer-season breeding flight, eluded our efforts to get a clear sound sample or photograph. But then again, two out of three ain’t bad.

The Coastal Scissor Grinder (Neotibicen latifasciatus), a species of subclimax maritime forests…

Davis’ Southeastern Dog-day Cicada (Neotibicen davisi), a species of long-needle pine forests…

To learn more about these and other regional cicadas, be certain to visit our cicadas page by clicking the “Cicadas” tab at the top of this page. Once there, you’ll now find sound recordings of thirteen species of periodical and annual cicadas regularly found in the Lower Susquehanna River Watershed or adjacent portions of the Atlantic Coastal Plain including Delmarva. Take a listen.

The editor’s 50-year-old pup tent at our temporary headquarters among the Loblolly Pines and maritime dune forest of Cape Henlopen State Park in Sussex County, Delaware. He enjoyed these deluxe accommodations, but received no new cap.

September 7, 2026September 10, 2026

Muddin’, Just a Harmless Pastime?

It looks irresistible—doesn’t it? To members of the gasoline and gunpowder gang and for exuberant youthful wannabes, this puddle alongside a forest road has “let’s go muddin'” written all over it. It’s an opportunity to rev ‘er up and slash on through to lay waste to those placid waters while draping the car, truck, cycle, or ATV with gobs of soggy slop. It’s an act of spectacular courage that afterward deserves a lap among one’s peers to display the cakes of dried muck worn as decorations of honor.

Rain Pool along Forest Road — A pool of rainwater along a forest road isn’t a mud puddle until subjected to the hedonistic impulses of a dopamine-craving operator of a motor vehicle of other conveyance. In many areas, these puddles often provide the only remaining ephemeral waters available to reproducing amphibians and other forms of life. Their presence along linear roads may help prevent population fragmentation, facilitating genetic mixture to eliminate inbreeding among otherwise isolated colonies of toads, frogs, and salamanders.

Gray Tree Frogs Eating Diatoms — In this pool, we found about four dozen Gray Tree Frog (Dryophytes versicolor) tadpoles feeding on tiny green clusters of diatoms. Diatoms are microscopic phytoplankton that grow in almost any water that contains the silica necessary for the formation of their cell walls. During photosynthesis, diatoms generate as much as half the world’s supply of oxygen and fix enormous quantities of carbon dioxide. They may make up half the biomass of global oceans. As rain rehydrates dried up puddles along forest roads, diatoms are frequently the first sign of life to return.

Sahara Dust Cloud Composed of Diatoms — The dust clouds that blow from the African Sahara to fertilize the Amazon Basin and the waters of the Caribbean are largely the silicate-rich remains of long-dead diatoms. (NOAA/GOES-19 image)

Daphnia and Anopheles — Tree frogs aren’t the only thing eating diatoms in the rain pool, Daphnia, seen here as rufous-brown specks, are a zooplankton often called “water fleas”. Their eggs are durable and can withstand periods when the puddle has no water. Another consumer of diatoms, and an ideal tadpole food, is mosquito larvae. They hatch within days of adults finding the pool and depositing eggs. Two worm-like Anopheles mosquito larvae are seen here, one in the water atop the upper middle portion of the leaf and the second floating to its upper right. In eastern North America, this genus of mosquitos includes the Anopheles quadrimaculatus complex, the Common Malaria Mosquitos from which the disease-causing Plasmodium parasites have been eradicated in our region.

Gray Tree Frog Eating Daphnia — After starting life as primary consumers feeding upon diatoms, Gray Tree Frog tadpoles become secondary consumers, snapping up mosquito eggs and larvae as well as the plentiful Daphnia.

Gray Tree Frog and Daphnia — A Gray Tree Frog tadpole feeding on Daphnia, a minute crustacean sometimes known as a “water flea”.

The Gray Tree Frog tadpoles we found in this roadside pool will mature this fall to live an arboreal life among the trees of the forest. Next year, they may return to the same puddle ecosystems where they themselves were born to mate, lay eggs, and start a new generation. (United States Fish and Wildlife Service image by Sara Hollerich)

Knowing what you now know, how could you ever go crashing through a rain pool again? You wouldn’t want to leave your mother worrying that she raised an eternally adolescent jackass, would you? Or worse yet, a sociopath? After all, you’d never drive up on a sidewalk full of puppies, would you?

September 6, 2026September 6, 2026

A Friendly Little Fly

White-faced/Hornworm Tachinid Fly — While finding a fly alighting upon a putrefying piece of meat wouldn’t seem all that unusual, you may be surprised to know that this fly has no real attraction to dead and decaying animals at all. This adult tachinid fly, probably Archytas apicifer, is a nectar-feeding pollinator of flowering plants. And this rotting chunk of carne is just the editor’s wrist from which it is lapping up some salt and other minerals.

August 25, 2026August 25, 2026

What Happened to the Butterflies?

Uncle Tyler Dyer wants to know, “What happened to all the butterflies. Man, I’m worried. I’m seeing just one or two of the common species, but not in anywhere near the numbers we usually see by this time of year.” His question is a rhetorical one. He understands the contributing factors that have conspired to diminish, fragment, and even eliminate populations of butterflies and other insects throughout much of the lower Susquehanna valley.

Here at susquehannawildlife.net headquarters, we’ve observed but four or five species this year, and only several individuals of each. Despite our efforts to devote every square inch of available space in our gardens and pools to plants that benefit butterflies and other insects, we can only do so much. Much like other areas of the region, our compact parcel is surrounded by more and more pavement, manicured lawn, and properties planted with commercially produced ornamentals cultivated to look good, grow fast, and not attract “insect pests”. To butterflies, the land beyond our little border is a desert.

Among human habitations where there may sometimes be an effort to provide nectar for pollinators including adult butterflies, the surrounding landscape still remains largely composed mostly of asphalt, cement, mowed turf, and tanbark-covered ground that offers few if any host plants for butterfly eggs and caterpillars, and no winter cover for our resident species. In the farmlands, herbicide-tolerant crops treated with systemic insecticides are grown on ground sterilized against the emergence of any potential butterfly host species—no mustards, milkweeds, native grasses, violets, or indigenous legumes. Just look at that barren ag ground in January, no butterfly survives there.

Application of herbicides and insecticides is more widespread than you might think. Few plots of ground in proximity to human activity experience a year without use of at least one dose of a pesticide. Along the highway, in the field, on the lawn, in the trees, across the forest, in the soil, on the water, around the garden, about the house—it’s pure poison to insects and/or their host plants and they don’t survive it.

Great Spangled Fritillaries readily visit milkweed blooms for nectar, but by late summer, require violets upon which they can lay their eggs. As they overwinter on the remains of the violet, the eggs must remain undisturbed. Then, in spring, the caterpillars hatch to feed upon a fresh new growth of violet leaves.

This Zebra Swallowtail enjoys the nectar provided by flowering plants in a pollinator meadow along the Susquehanna River. However, when it comes time to reproduce, this butterfly relies on stands of its larval host plant, the Common Pawpaw, a small tree that grows mostly in the understory of riverine forests. Some of our local pawpaw habitats have already been destroyed by housing development and other construction both in low-lying terrain and in the river hills. Meanwhile, surviving groves of woodland pawpaw are threatened by Japanese Knotweed (*Reynoutria japonica)*, honeysuckles, privets, and other invasive species. Unfortunately, the host plants for many other butterflies face these same threats.

Here at susquehannawildlife.net headquarters, our most common butterfly this summer has been the Monarch. Considering the numeric loses this species has experienced in recent years, its good news for the Monarchs but not so great news for the butterflies we typically see in good numbers and have not.

While their wintering habitat in Mexico faces potentially catastrophic loses due to clandestine logging and other criminal activity, Monarchs do have an advantage once they come north to breed. While other butterflies mate and deposit eggs close to where they themselves were hatched and completed their metamorphosis into adults, each in the succession of each year’s several generations of Monarchs will roam widely in search of suitable stands of milkweed upon which they can lay their eggs.

Monarch Caterpillars Eating Butterflyweed — These are the fast-growing caterpillars hatched from eggs deposited by a pair of Monarchs that found our urban garden. Just yesterday, we discovered them munching away on the foliage of Butterflyweed, a species of milkweed. Other milkweeds in our micro-refuge include Common Milkweed and Swamp Milkweed.

Other than in the few scattered places where habitat is managed for them, butterflies and other insects don’t fare well in proximity to human activity. This is especially true in the Lower Susquehanna River Watershed where an already neat and tidy culture has become obsessed with a cleared landscape and thus compulsively sprays, mows, whacks, and cuts away at the habitat critical to the survival of hundreds, maybe thousands, of species of these indispensable invertebrates. Take a walk or a drive and look around. Other than a hanging basket of flowers that may or may not have been treated with poisonous neonicotinoids, there’s no place for a butterfly, let alone its progeny, to survive. Just listen…that motorized, grinding racket outside is the sound of butterfly habitat being destroyed, April through November, day after day, year after year.

As for Uncle Ty, he’s putting in a little more effort. Scattered sanctuaries for butterflies aren’t going to save them from the wholesale fragmentation of their habitat that has been intensifying in recent years. Less than 1% of landowners actually rewild property or manage at the ecosystem level, so more must get involved. Uncle Ty asked us to pass along this guide to Butterfly Habitat Management from the United States Department of Agriculture’s Natural Resources Conservation Service. He’s used tips from the publication for years and highly recommends the list of host plants it includes.

Click this image to download the Butterfly Habitat Management bulletin from the United States Department of Agriculture’s Natural Resources Conservation Service. Though this publication is a bit dated, the concepts remain sound and many of the programs listed for planning, funding, and construction assistance remain active.

An Eastern Tiger Swallowtail feeds on nectar while unknowingly pollinating wildflowers in a butterfly meadow. For this swallowtail species to survive, forests or wooded parkland with Yellow Poplar (Tuliptree) and other host plants must be provided nearby. Less than one in one hundred landowners actually go the extra step to implement ecosystem-level habitat management on their property. Butterflies and other wildlife won’t survive unless they have a lot more participation from a lot more friends.

August 19, 2026August 21, 2026

Annual Cicadas Singing at Last

Today, after a wait of about a month, we finally began hearing the belated trills, whines, and rattles of notable numbers of annual cicadas. During the day’s excursions, we identified the songs of each of the five species commonly encountered in the lower Susquehanna valley, but were especially surprised to photograph and make a sound recording of something we had previously failed to observe well enough to identify in detail.

"Engelhardt's Cicada" — This annual cicada found on the lookout at Second Mountain Hawk Watch on the border between Fort Indiantown Gap Military Reservation and State Game Lands 211 (St. Anthony’s Wilderness) in northern Lebanon County, Pennsylvania, didn’t appear to be anything too special. Perhaps it was one of the numerous Swamp Cicadas we had detected nearby as they droned. Then no, by the sound of this individual’s song, it seemed to be one of the more difficult to observe species, a Lyric Cicada (Neotibicen lyricen), an insect most commonly found among treetops in deciduous woods and mature suburban gardens. It was another case of identification by ear, but then again, we hear them well at lot more often than we see them well.

August 4, 2026August 4, 2026

Photo of the Day

Female Southern Spreadwing — While other damselflies hold their wings together in an upright position while pausing for a break, spreadwings are recognized by the way they rest their wings horizontally like a dragonfly while perched. Earlier this morning, this female Southern Spreadwing (Lestes australis) visited the vegetated pools at susquehannawildlife.net headquarters. It’s likely that she’s wandering widely to forage on flying insects during the couple of weeks needed to reach maturation before her move to a more sizeable lake or pond to find a mate and breed.

August 3, 2026August 3, 2026

Photo of the Day

Ringed or Sycamore Assassin Bug — The Ringed Assassin Bug (Pselliopus cinctus) is an ambush predator that stalks its victims on flowering plants in gardens, meadows, and forest margins. It disables its prey by injecting it with digestive juices before consuming the liquefied internals like a milkshake through a straw. Wait, wasn’t that the plot for one of those low-budget 1950s horror flicks? Yeah, I remember it now; they were peddling grasshopper shakes at the snack bar during the intermission and the sales were through the roof. Well, maybe not. Although the Ringed Assassin Bug sometimes takes a pollinating insect like a leafcutter bee, its most frequent targets are flies, aphids, leafhoppers, and various caterpillars. Pselliopus cinctus is sometimes called the Sycamore Assassin Bug, though you’re not likely to ever find them on these lowland trees.

July 30, 2026August 1, 2026

Meet the Beetles

No, this is not an account chronicling a British invasion, especially during the month we celebrate the country’s 250th anniversary of its separation from commonwealth rule. This is instead a short introduction to some of the numerous regional insects of the order Coleoptera.

Globally, there are somewhere between 300,000 and 2 million or more species of beetles, depending on who’s doing the enumerating. A commonly settled upon number is 400,000, which makes beetles account for about 40% of the known insect species and 25% of the animals in the world. In the United States, there are almost 30,000 species.

Morphological variation among individuals in a population of beetles is easily observed. These differences often manifest into adaptations that provide a survival advantage and speciation. It therefore comes as no surprise that beetles were among the life forms studied by Charles Darwin as he pondered natural selection and preparation of The Origin of Species.

Beetle Display at North Museum — During the nineteenth century, Professor Samuel Stehman Haldeman and other members of the Linnaean Society of Lancaster City and County made sizeable collections of beetles. Haldeman mentored society treasurer Simon S. Rathvon’s interest in the insects and he in turn curated the 12,000 beetles in the society’s holdings. The beetle case seen in the photograph is on display at the North Museum on the campus of Franklin and Marshall College in Lancaster. Many of the Linnaean Society of Lancaster City and County’s specimens were moved from the custody of the college to the museum upon its opening in 1953. (For more on the Lancaster Linnaeans, see our post from February 25, 2018, titled “A Century of Extinction” or, better yet, visit the North Museum.)

If it’s organic, living or dead, a beetle has probably become specially adapted to fill the role of reducing it or consuming it. Beetles are indispensable members of the ecosystems they inhabit. Many function as scavengers, breaking down dead plants or animals into the basic nutrients that renew life. There are those that consume rotting wood, dung, and carrion. Sometimes they eat these things when people would rather they didn’t—such as moist wood that’s part of a house. Then there are species of beetles that are herbivores, consuming parts of the plants that get their energy directly from the sun. There are beetles that eat stems, roots, leaves, buds, flowers, nectar, sap, seeds, and fruit—many specializing in particular plant species or families. Some of these herbivorous primary consumers come to our attention because their populations explode in response to our creation of monocultures of their favored food, but many more act as pollinators for plants critical to human survival. Linnaean Society treasurer Rathvon made these herbivore-plant relationships the focus of many of his nineteenth-century writings, particularly as they affected agriculture. On the upper trophic levels, there are the predatory beetles that feed on herbivores or other carnivores. Many of these species have narrowed their choice of prey to one or fewer species. For example, there is a beetle that feeds only on the subterranean nymphs of cicadas.

Beetles and Trophic Levels — Beetles occupy numerous trophic levels within the food chain. Staghorn or stag beetle (Lucanidae) larvae are reducers that feed on rotting wood. Meanwhile the adults, which are sometimes attracted to man-made lights, consume sap. A herbivorous primary consumer, the Red Milkweed Beetle (Tetraopes tetrophthalmus), a member of the long-horned beetle family (Cerambycidae), feeds exclusively on Common Milkweed. Ladybird beetles (Coccinellidae), also known as ladybugs, are secondary consumers and favorites of gardeners due to their appetite for aphids throughout most of their lives. (Click the image for a larger version)

Ladies and gentlemen, the beetles…

The Dogbane Beetle (Chrysochus auratus) is one of the leaf beetles (Chrysomelidae), a family which includes numerous agricultural pests. However, as its name suggests, this beetle feeds on dogbane (Apocynum species), a milkweed-like plant of woodland edges and early successional habitats, so it poses no threat to crops or ornamentals.

May Beetles or Junebugs — The large family of scarab beetles (Scarabaeidae) includes dung beetles and other important detritus-feeding decomposers. The may beetles, also known as junebugs, seen here are probably of the genus Phyllophaga, but species-level identification typically requires lab examination.

May Beetle or Junebug — Adult may beetles feed on a variety of leaves throughout the night. The larvae consume the roots of grasses and other plants. Neither life stage does significant damage, but skunks have a passion for digging in lawns to find the larval grubs.

Big Brown Bats are the only commonly encountered flying mammal remaining in the lower Susquehanna valley. To provide the nutrition and energy they need to raise young and store up reserves for hibernation, Big Brown Bats consume large quantities of night-flying scarab beetles (including Phyllophaga species) throughout the summer and fall. In addition, their survival relies in large part upon the availability of adequate summertime birthing roosts in places like warm attics. Later in the year, their needs shift to wintering sites in caves, mines, and quiet old cellars where they don’t need to share space with colonies infected by the fungus Pseudogymnoascus destructans, the pathogen that causes White-nose Syndrome (WNS), a fatal disease that has wiped out 95% of the bats in some hibernacula. (United States Fish and Wildlife Service image by Pete Pattavina)

Adult Green June Beetles, also known as June Bugs, are often most evident in July. These diurnal herbivores normally consume fruit like this watermelon only after it begins rotting or has been damaged by some other animal. The larvae are mostly detrivores, specializing in consuming mold and humus, especially among the roots of plants that lie beneath layers of mulch or thatch. The grubs are preyed upon by skunks, birds, and moles.

Striped Skunk — Skunks digging among grasses are often harvesting the larvae of many different species of scarab beetles.

Eastern Bluebird Eating Mealworm — Mealworms are the commercially raised larvae of the Yellow Mealworm Beetle (Tenebrio molitor), a species of darkling beetle in the family Tenebrionidae. Perpetual pests in food storage, the grubs are now raised for research and as food for humans and insectivorous animals like this Eastern Bluebird supplementing its winter diet at our headquarters feeding station.

Click beetles (Elateridae) have an articulating prothorax that snaps and propels the insect into the air as a protrusion resembling a spine “clicks” into a furrow on its ventral surface. These sudden launches can help the click beetle escape a potential predator.

Like the previous individual, this click beetle was attracted to man-made light. The larvae consume small rootlets, seeds, and tubers in soil and among decaying organic matter.

Another member of the click beetle family, the Eyed Elator (Alaus oculatus) mimics the head of a snake or other predator to avoid assuming the role of victim. The larvae feed among the stumps and roots of dead and dying forest trees consuming the larvae of wood-boring insects.

The Six-spotted Tiger Beetle (Cicindela sexgutata) is a familiar sight on sun-dappled forest paths. It is a fast-running predator, consuming ants, spiders, and other small arthropods. The larvae ambush hunt from the entrance to their burrow, quickly snagging prey as it passes by.

The aquatic larvae of the Giant Water Scavenger Beetle (Hydrophilus triangularis) are voracious predators consuming snails, other invertebrates, tadpoles, and even small fish. In some waters, they may contribute to the control of mosquitos. The adults are herbivores and scavengers. Some, like this one, are attracted to lights at night.

Photinus Firefly — Fireflies, also known as lightning bugs, are renowned for their ability to produce a flash of light to attract a mate on a warm summer evening. Both sexes of fireflies in the genus Photinus (seen here) produce pulses of yellow light through the chemical reaction known as bioluminescence. Their larvae feed mostly on earthworms. The genus Photuris includes the Pennsylvania Firefly (Photuris pennsylvanica), the keystone state’s official insect, but a beetle that is not particularly plentiful in the commonwealth. Photuris flashes are greenish in color and begin a bit later, usually after dark. Their larvae are scavengers, consuming fallen insects and fruits. A third genus, Pyractomena, flashes amber light. Its larvae consume snails and can be seen ascending vegetation above damp soil along the shorelines of quiet segments of the lower Susquehanna River at nightfall.

Photinus pyralis, the Common Eastern Firefly, is the most widespread and numerous “lightning bug” in the Lower Susquehanna River Watershed. Want to see more fireflies around your place next summer? It’s easier then you might think. Just turn out the lights, skip the the lawn treatments, and let more space rewild to tall, mature grass and herbaceous growth, then watch the magic. The star-like twinkles of glowing beetles will be signaling, “I want to hold your hand,” throughout your private firefly refuge.

Male Common Eastern Firefly "Dipping" — Because the male Common Eastern Firefly dips downward then makes an upward swing while illuminating, the species is also known by the common name Big Dipper Firefly.

July 6, 2026July 6, 2026

Are Ants Invading your Summertime Picnic? Not in Our Neck of the Woods

If sprinkles of pepper are the only black specks you care to find in your potato salad, and if the only thing you want in your pants is you, then having a swarm of ants visit your outdoor feast is out of the question. During our recent multi-day foray afield, ants were just a cupcake’s throw away, but none dared to scurry out from their hiding place to invade our spread. Fortunately for us, the local anteater was on duty, snatching them up whenever they came into sight—and sometimes before.

We’re all familiar with the Pileated Woodpecker, the prehistoric-looking, pterodactyl-like denizen of the forest whose appearance alone reminds us that birds are the surviving dinosaurs.

Carpenter Ants — Carpenter ants (Camponotus species) don’t eat wood, but instead excavate extensive nests called galleries in damp and rotting timber. Considered both predators and scavengers, they get most of their nourishment by harvesting nectar from flowering plants, by extracting the gooey tissues and liquids from dead insects, by using their antennas to coax honeydew from the aphids they farm, and by carrying away sweet treats unwittingly provided by humans. The Pileated Woodpecker’s long anteater-like tongue is an adaptation for feeding on these ants and other creepy crawlies. Carpenter ants often make up a majority of a Pileated Woodpecker’s diet, particularly during the warmer months of the year. They are one of the first foods young woodpeckers can easily locate and consume on their own. During the colder months, when ants can be harder to find, Pileated Woodpeckers seek out overwintering beetle grubs and other larvae while also foraging for energy-replenishing berries including Poison Ivy, wild grape, and bittersweet.

June 27, 2026June 28, 2026

Swarms of Sulfurs

Balmy evenings and rising stream temperatures are yielding some sizeable flights of mayflies collectively known as sulfurs. These nuptial displays are most conspicuous as swarms attracted to bright lights near the waterways where the aquatic nymphs spent the past year or more before emerging to take wing for their brief period of adulthood. During the past two nights here at susquehannawildlife.net headquarters, we’ve noted what appear to be three different species of these tiny sulfurs gathering on the walls and doors below entry lamps. Each is referred to by anglers using the common name “Pale Evening Dun”.

Sub-adult (Subimago) Leucrocuta aphrodite — Flat-headed mayflies we believe to be Leucrocuta aphrodite, this one a subimago (sub-adult) yet to undergo its final molt, continue their emergence for a third week.

Adult (Imago) Leucrocuta aphrodite — Just one of many imago (adult) Leucrocuta aphrodite mayflies seen paying us a visit.

Sub-adult (Subimago) Leucrocuta minerva — Though similar in size to the prior specimens (about one half inch in length), this flat-headed mayfly subimago (sub-adult) may be a different species, possibly Leucrocuta minerva. We first noticed the arrival of these mayflies early last evening.

Adult (Imago) Leucrocuta minerva — A possible imago (adult) Leucrocuta minerva.

Sub-adult (Subimago) Ephemerella dorothea — Like the preceding mayflies, this sulfur is also referred to as the “Pale Evening Dun”, though you’ll notice it has three tails instead of two and is noticeably larger, approaching one inch in total length. Unlike the flat-headed mayflies (family Heptageniidae) which possess compressed bodies for clinging to rocks and other substrate in the riffles and pools of high-gradient streams, this spiny crawler mayfly (family Ephemerellidae) inhabits lower-gradient waters where it not only clings, but crawls and swims as a means of locomotion. The subimago (sub-adult) seen here is a member of the genus Ephemerella, probably the species E. dorothea. To many fly-tying anglers, it is also known as the “Pale Morning Dun”, the “Little Sulfur Mayfly”, or the “Summer Mayfly”.

June 26, 2026June 26, 2026

Photo of the Day

What happens when a single native plant species like this Oxeye (or False Sunflower) becomes exceptionally common in a forest margin? Well, that stand of Oxeye becomes vulnerable to a runaway infestation of sap-sucking insects like these colorful Dusky-tailed Sunflower Aphids (Uroleucon obscuricaudatum). Because each of our many native aphid species specialize to feed on only one species, genus, or family of plants, these localized aphid booms seldom threaten the overall population of the host. Aphids target soft new growth, so plants that escape infestation in the early part of the growing season have a chance to harden off and thereafter flower, seed, and mature unscathed by these little suckers. After all, if a specialized feeder like the Dusky-tailed Sunflower Aphid wiped out all of the sunflowers and false sunflowers in its range, Dusky-tailed Sunflower Aphids would cease to exist. Look at it this way, aphids do a little thinning to help promote plant diversity in their landscape.

June 11, 2026June 28, 2026

Mayflies and Hitchhikers

Month-by-month and week-by-week changes in water temperatures and other stream parameters trigger the date-specific emergence of flights of particular species of mayflies from the lotic waters where they spend a year or more feeding and growing as substrate-dwelling nymphs. For each individual mayfly, these nuptial flights are only days in duration and include a molt from the sub-adult (subimago or dun) stage to the adult (imago or spinner) stage. Mayflies do not feed during these flights, their sole intention is to mate and reproduce. Conspicuous transitions of large numbers of nymphal mayflies into flying sub-adults are often referred to as “hatches”. So, what’s hatching right now? As local streams reach the upper sixties and seventies, we’ve noticed this mayfly gathering on walls and windows illuminated by man-made light, sometimes a half mile distant from the waterway where they spent the past year or more as a nymph before first taking flight…

A subimago Leucrocuta aphrodite — A possible subimago (sub-adult) Leucrocuta aphrodite, a flat-headed mayfly sometimes called the “Pale Evening Dun”, a common name applied primarily by fly-fishing anglers to several not-so-closely-related genera of mayflies also collectively known as sulfurs. Flat-headed mayflies (family Heptageniidae) are adapted to nymphal life in stream riffles where their low profile helps them cling to the rocks where they feed.

Leucrocuta aphrodite Exuvia with a phoretic mite. — Soon after taking flight, the sub-adult (subimago) Leucrocuta aphrodite molts into a second flying stage, that of the breeding adult (imago), leaving behind its final exuvia. This particular exuvia has a stranded hitchhiker on the abdominal section. Phoretic mites (Acariformes, in part) are thus named because they practice phoresy, attaching to hosts for no other purpose than transportation. Just how small is this little, red-brown mite? Well, the entire mayfly, including tails, is only about one-half-inch long.

May 19, 2026June 5, 2026

The Stewards of Inland Shorebird Habitat

As they travel between coastal wintering ranges and breeding territories in Canada and Alaska, vast numbers of shorebirds pass through the lower Susquehanna region each spring and fall—though few stop here to rest, feed, and provide us with an opportunity to observe them. Prior to the construction of man-made dams and other alterations on our lotic (flowing) waterways including the river, shorebirds took advantage of lateral bars, stream deltas, and other alluvial deposits as places to loaf and re-energize. Before they were drained and filled, some of the valley’s wetlands probably included sparsely vegetated flats where shorebirds could drop in for a brief visit. Previous to their extirpation from our region, North American Beavers were the primary providers of quality habitat for shorebirds and other migrating waders on our lotic waters. Their widespread network of dams, pools, and marshes maximized floodplain function by keeping streams thoroughly connected to their wetlands, nurturing plant communities that not only provided food and shelter for the beavers and other wildlife, but provided superb buffering against erosion while protecting against sediment and nutrient imbalances in lower Susquehanna waterways.

Beaver Dam and Lodge — Beaver dams need not be large, particularly on low-gradient streams where a structure like this is sufficient to create a pool with depth adequate for building and maintaining a lodge and transporting leafy branches and other food items by water.

A beaver lodge assembled in a pool with less than three feet of water, deep enough to provide the family with a measure of protection against terrestrial predators.

Beaver Pool — Beaver pool ecosystems provide homes for hundreds of species of plants and animals, including migrating shorebirds and other waders.

Mud flats in the margins between emergent shrubs and herbaceous plant growth attract migrating shorebirds like this Solitary Sandpiper to the abundance of invertebrate life. Seasonal movements of migrating shorebirds regularly coincide with the reductions of water levels in beaver pools which typically occur between May and September each year.

During its southbound migration in September, a Least Sandpiper searches for arthropods and annelids as it visits a food-rich puddle along the periphery of a beaver pool.

A Pectoral Sandpiper feeds in shallow water near a stand of Common Cattails in a beaver pool.

During migration, rails including the Sora are attracted to dense emergent vegetation in beaver pools. Some will nest in these rodent-managed refugia.

Green Herons visit beaver pools during migration and, due to the reliability of the food supply, will often nest in their vicinity.

So how did this happen? How did the North American Beaver become a keystone species—an animal upon which the majority of other life forms within its ecosystem are so reliant? Well, it’s largely due to the fact that our beavers aren’t particularly fond of a constant stream of noise. More specifically, they don’t like the sound of running water in places where they intend to build and maintain a lodge. And so, as they begin to place sticks, mud, limbs, stones, and other materials within a noisy riffle on a stream, they create a dam, and behind it a pool—a pool that is particularly advantageous for protecting their home and providing a means of conveyance for their construction materials and food supplies.

Cascading Series of Beaver Pools — On a high-gradient segment of stream, beavers will create a cascading series of pools. Because water filters through a beaver dam instead of spilling over it, the work of these meticulous rodents soon silences the sounds of water changing altitude. No more sonorous riffle.

Beaver Dam — **Quiet please.** High seasonal stream flow and damage from storms may create areas where water begins to erode the structure of the dam. Where this condition persists, an adult beaver will soon mend the breach, just to quiet things down. Why would beavers demand such a hush upon their domain? Well, they have poor eyesight, but their hearing is excellent, and they rely upon it to detect danger.

The Louisiana Waterthrush (Parkesia motacilla), one of our earliest-arriving warblers, nests in forests along clear, high-gradient streams. In mid-April, we found this individual and three others squabbling over a breeding territory adjacent to the series of cascading beaver pools shown in the previous images.

Brook Trout and Blacknose Dace — Native denizens of coldwater streams, neither the Brook Trout nor the Eastern Blacknose Dace has any difficulty finding its way through the voids in beaver dams to ascend and descend the sequence of pools.

Beaver Dam and Pool on Low-gradient Stream — On a low-gradient segment of stream, a dam just over a foot in height may be sufficient to create a beaver pool of considerable size. Resembling the water-logged muskeg of the far north, well-established beaver pools form boggy habitats familiar to migrating shorebirds.

Water levels in the pools usually drop along with the stream’s base flow as soon as the effects of the spring thaw and rain showers subside. Feeding areas in shallow water and on muddy ground are often revealed just in time for northbound shorebirds and other waders to stop by in late April and May. These conditions often persist through the growing season and the fall migration of these birds which begins as early as late June and sometimes extends into October.

Tree Swallow at Natural Cavity — Where the pool inundates standing timber such as Red Maple and other species not used by beavers, the dead snags provide vital feeding areas for birds and other wildlife. Cavity nesters like this Tree Swallow seldom find suitable natural housing elsewhere.

Eastern Newts Among Alderfly Exuvia — The mosaic of marshlands and braided stream channels within the beaver pool complex supports an abundance of aquatic life including these breeding Eastern Newts, seen here surrounded by the exuvia left behind following a massive hatch of alderflies (Sialinae). Alderflies are a stream inhabitant during their larval stage and are indicator of clean water conditions.

**A modern-day example of the way fully functional stream floodplains used to look in the Lower Susquehanna River Watershed.** Though the pools may appear pond-like during the cooler and wetter months of the year, by summer the water levels behind the beaver dams recede as the base flow of the stream wanes. Now the true nature of the marsh, shallow pool, and braided stream complex is revealed. Unlike most man-made dams that set a fixed pool elevation regardless of flow by discharging water over the top of the structure or through a spillway or gate, beaver dams merely throttle the flow through their porous construction. Unless the beaver begins plugging small leaks as fast as the stream flow ebbs, the water level in the pools will drop. So they’re not left high and dry, lodges are located in the deepest pools, usually in close proximity to the dam and/or one of the stream courses. Though not inundated during the dry season, the soil in the pool complex is almost always damp and plants grow vigorously there, sequestering nutrients and retaining sediments in beneficial deposition patterns that actually inhibit erosion of the riparian landscape. These streams and floodplains retain their hyporheic zone and freely exchange water with the underlying water table and aquifer. It’s the ultimate floodplain management system, and the beavers don’t even know their doing all the work. (Google Maps base image)

Where another high-gradient segment of stream enters the main pool complex, beavers have created an additional series of cascading pools. The impoundments created by these dams help diffuse stormwater energy and process more nutrients and sediments within the floodplain’s wetland vegetation system. (Google Maps base image)

Sandhill Cranes in Beaver Pool — Beaver pools often refill as stream flows increase following autumn rains. The stockpiles of vegetative foods that grew within the beaver’s domain through the summer then become flooded and are a prime source of nutrition for not only the beavers, but waterfowl during both their autumn and spring migrations. Gleaning and probing Sandhill Cranes often find these habitats to their liking as well.

While North American Beavers have returned to the region, most live as “bank beavers”, residing in the river and larger creeks of the valley where they excavate shelters among the roots of Black Willows and other shoreline trees and shrubs. Floodplain encroachment, legacy sediment deposits, and just plain human intolerance have all conspired to prohibit North American Beavers from performing their magic on smaller local streams. For migrating shorebirds, this continued absence of beaver dam ecosystems has turned much of the lower Susquehanna valley into “flyover country”. Those travelers that do stop to rest and feed concentrate at the few favorable locations such as the lateral bars and the hydroelectric dam-created delta at the Conejohela Flats on the river in Lancaster County. But centralization has its drawbacks. Migrants spending time at concentration points may have a greater chance of contracting and spreading disease. Protracted heavy foraging can degrade these habitats. And over time, features such the lateral bars and delta deposits, including those on the Conejohela Flats, transition into other habitats—riparian forests. A more widespread selection of favorable stopover points for shorebirds, waders, waterfowl, and other migrants is certainly desirable.

IMITATION IS THE SINCEREST FORM OF FLATTERY

Until public sentiment sways in favor of the North American Beaver, wildlife managers are mimicking some of the attributes of their sound-inspired installations.

New Impoundment at Middle Creek Wildlife Management Area — Created by excavating a depression in heavy clay soils, this new impoundment at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area collects water directly from rainfall and from surface runoff. Its depth at no point is greater than about two or three feet. During the driest times of the year, this space will be a mudflat, and a haven for migrating shorebirds.

Shallow-water conservation impoundments designed, constructed, and managed for migratory waterfowl and waders including shorebirds are not what we typically refer to as ponds—though they are lentic (still) waters. Similar shallow freshwater impoundments at our National Wildlife Refuges are referred to as pools by the United States Fish and Wildlife Service, but smaller versions like this example at Middle Creek very closely resemble the prairie potholes created by glacial scour in the north-central United States and adjacent portions of Canada. Many populations of migratory birds are familiar with pothole ecosystems and, like the beaver pools and marshes, have relied upon them as waypoints along their journeys for centuries.

Pond and Lake Zonation — Impoundments most beneficial to migrating waterfowl and waders including shorebirds are shallow in depth. They lack the deeper waters of a pond or lake and thus have no limnetic (open water) or aphotic zones. Managed throughout as a littoral zone, impoundments grow plants in shallow water or on damp soil through the summer months to chew up nutrients accumulated in waste deposited by visiting birds. This vegetation is then flooded from late fall through early spring as forage habitat for migratory waterfowl. The timing of the fluctuations in water levels approximates those of the beaver pools and marshes on lotic (flowing) waters.

Impoundment Gate — A gate assembly is a water control structure installed to provide seasonal management of the water levels in a conservation impoundment. More than once, beavers have heard the sounds of tumbling waters inside these types of devices and tried to dam them up!

You’ve heard the line, “If you build it, they will come.” Well, it’s true. Here is a sample of the activity witnessed during the past two weeks at the new impoundment completed just several months ago at Middle Creek Wildlife Management Area along the tour route just beyond the “Stop 3” overlook.

The ubiquitous Snow Geese were among the first migratory occupants of the new impoundment. A few are currently lingering in the vicinity.

Ducks soon followed. These Blue-winged Teal were among the last to pass through earlier this month.

Wilson's Snipe — Wilson’s Snipe were among the first species of migratory shorebirds to visit the new impoundment at Middle Creek…

…as were Killdeer, a species which nests nearby.

Then, earlier this month, flocks of shorebirds including these Least Sandpipers were arriving to feed and rest.

Least Sandpiper and a Semipalmated Sandpiper — A Least Sandpiper (left) and a Semipalmated Sandpiper (right).

White-rumped, Least, and Solitary Sandpipers — Here’s a Solitary Sandpiper (right) feeding alongside a Least Sandpiper (center) and a White-rumped Sandpiper (left).

Least Sandpiper and a White-rumped Sandpiper — A Least Sandpiper (left) and a White-rumped Sandpiper (right).

Rare in our area during spring, the White-rumped Sandpiper (Calidris fuscicollis) flies north using the central flyway, then heads south along the Atlantic flyway in the fall, when it tends to be more regular here.

Rocking and teetering along as it looks for food, the Spotted Sandpiper may be one of the easiest of shorebirds to identify.

Chunky little Dunlin (Calidris alpina) with their conspicuously down-curved bills are another easy-to-identify species, particularly in the spring when their breeding (alternate) plumage includes a black belly.

Black-bellied Plovers acquire a handsome set of plumage in the spring as well.

The Semipalmated Plover doesn’t have nearly the flair for ornament its close relatives the Killdeer do; these little shorebirds wear only one ring around their neck instead of two. Think this plover is cute?,…

Speaking of legs, here’s one of dozens of Lesser Yellowlegs that visited the new impoundment during their recent northbound travels.

Though less numerous than the smaller Lesser Yellowlegs, a Greater Yellowlegs seldom goes unnoticed when dropping by the man-made pothole habitat.

Wilson's Phalarope — Everyone likes to see something unusual every now and then, and this impoundment delivers. Just yesterday, we photographed this migrating Wilson’s Phalarope (top center) among two Least Sandpipers (top left and right), a Lesser Yellowlegs (left and slightly forward of the phalarope), and a White-rumped Sandpiper (foreground).

Species of wildlife in addition to shorebirds and waterfowl have already found the new impoundment favorable…

Pairs of breeding Spot-winged Gliders (Pantala hymenaea), seen here in tandem while ovipositing, were swarming the impoundment after arriving earlier this week. These dragonflies are ofttimes unpredictable nomads and are similar in appearance to the usually more numerous Wandering Gliders. To recolonize seasonal portions of their range, both are famous for hitching a ride en masse on storm systems. They share the behavior of finding ephemeral and new bodies of water favorable for egg laying due to their low density of aquatic predators.

We watched this Snapping Turtle arrive to apparently find the newly created waters to its liking. Snapping Turtles are important consumers in a wetland ecosystem. Larger specimens may fill the role of an upper trophic level or apex predator, eliminating vulnerable mid-level consumers including other Snapping Turtles.

Because it bounces its tail up and down like a Spotted Sandpiper, you may at first glance mistake an American Pipit for a shorebird. Long known as the Water Pipit, these songbirds have been visiting the impoundment while migrating north and stopping to feed in nearby croplands.

Seen here with Least Sandpipers is a visiting Glossy Ibis.

Western Cattle Egrets visiting Middle Creek this spring have been frequenting the new impoundment.

Western Cattle Egret — With still little in the way of insects such as grasshoppers available in the surrounding landscape,…

…cattle egrets are looking to find prey like this Green Frog.

Managing saturation levels in shallow-water impoundments to resemble the seasonal variations in beaver pool and marsh systems can create lush growth and wildlife-rich environments. Take a look at some images from a project in a headwaters area of a tributary to Conewago Creek (west)…

Well-established Shallow-water Impoundment — By late July, southbound shorebirds were already using these mudflats to feed and rest. Other sections of the impoundment were dense with emergent and aquatic plants, the latter kept hydrated in deeper pools of the project by the inflow from several captured springs that supplement direct rainfall and sheet runoff to supply its water. During a seasonal drawdown, the exposure of the impoundment’s soils to direct sunlight can provide a measure of disinfection to reduce the chances of disease transmission among its populations of visiting birds and other animals.

Water Lily Growth — In the deeper pools of the impoundment, water lilies and other aquatic plants grow in lush mats to provide cover and feeding areas for resident populations of breeding reptiles and amphibians.

Immature Little Blue Heron — …and this immature Little Blue Heron, a wanderer typical of more southern latitudes.

While walking the road among tall grasses in the supporting landscape surrounding this impoundment, we were at first startled when these Sandhill Cranes strode by going the other direction. We quietly kept moving,…

Sandhill Cranes with Colt — The hatching of this colt is testimony to the vital role wetland ecosystems play in the lives of hundreds of species. Whether they be beaver pools and marshes on lotic waters or man-made shallow lentic waters, each of these habitats is filling a void that left floodplains and other critical lowland biomes faltering. While they can’t replace the full-function floodplain management provided by an active beaver colony, shallow-water impoundments can provide relief for habitat-starved populations of the animals and plants that rely upon them. A constellation of these projects on lands public or private across the lower Susquehanna watershed could help provide refuge for many of our flora and fauna with the most desperately fragmented of ranges.

So that you can relax while observing the comings and goings at a pair of the lower Susquehanna valley’s man-made impoundments, the Pennsylvania Game Commission has erected two viewing pavilions for public use on its lands…

The Haldeman Island observation pavilion is located on State Game Lands 290 just upstream from the Juniata River’s mouth on the Susquehanna at Clark’s Ferry in Dauphin County.

Haldeman Island Pavilion — It overlooks not only the island’s man-made shallow-water impoundments and neighboring grasslands, but the hacking tower used in the 1970s to reintroduce Bald Eagles from Saskatchewan to the lower Susquehanna. Interpretive signs explain the conservation stories of habitats and the eagle reintroduction program.

Middle Creek W.M.A. Observation Pavilion — The observation pavilion at Middle Creek Wildlife Management Area is of similar construction to the one at Haldeman Island. It is accessed from the parking pull-off along the tour road at its intersection with Chapel Road, just before the right turn and incline that leads to the “Stop 3” grassland overlook.

It too includes numerous interpretive signs to help visitors understand impoundment management.

During the next two weeks, the exodus of migrating shorebirds now staged and feeding upon Atlantic Horseshoe Crab eggs on Delaware Bay will commence. During the evening of their departure from the bay, many of these birds cross portions of the Lower Susquehanna River Watershed, particularly east of the river. Stormy weather and other climatic conditions may force some of them to seek a place to put down temporarily, so keeping a close eye on the new pothole-like impoundment at Middle Creek may be a prudent move. After that, waders known as “post-breeding wanderers” can show up at any time. Then, beginning as early as late June, shorebirds begin moving south on a migration that can provide us with viewing opportunities into September and beyond. See you out there!

May 7, 2026May 8, 2026

Photo of the Day

Not sure how we happened to spot this little gem in the backlit glare of the late-morning sunshine. It’s a Red-banded Hairstreak perched at the end of an Eastern Red Cedar branch. The blossoms and seeds surrounding it are suspended in some minute cobwebs that snagged them as they sailed downward from nearby trees. These southeastern butterflies are regular spring and summer wanderers north of the Mason-Dixon line. The gusty southwest winds earlier this week were apparently sufficient to help transport this particular one to the Conewago Creek (east) valley of Lancaster County. The Red-banded Hairstreak is a member of the “groundstreak” group, its larvae feeding on decaying dead leaves.

May 6, 2026May 6, 2026

Photo of the Day

Outside susquehannawildlife.net headquarters this morning, we were delighted to find this nocturnal Luna Moth (Actias luna), one of the “giant silkworm moths”, clinging to the side of one of our bee houses. During hours of darkness, this male is on a mission of radar love, his feather-like antennae used to detect pheromones produced by ready-to-mate females. Host plants for larval Luna Moths include deciduous trees such as willows, beeches, hickories, cherries, alders, and hazelnuts. It just so happens that we’ve been growing several American Hazelnuts (Corylus americana) in the garden for the past two years. We’re hoping they’ll help attract a mate for this colossal beauty.

April 1, 2026May 29, 2026

Migrating Waterfowl on Lotic Fresh Waters

Lotic vs. Lentic Freshwater Ecosystems — Some comparative attributes of unspoiled lotic vs. lentic freshwater ecosystems. Low-gradient (slow-moving) lotic waters often create, and remain connected to, accompanying riverine wetlands (a lentic freshwater ecosystem). These swamps, marshes, and ditches absorb, purify, and infiltrate flood waters while supporting a diverse number of plant and animal species.

We frequently perceive all waterfowl migration to be synchronized with the conspicuous movements of familiar species like Snow Geese, Tundra Swans, and Canada Geese—big flights coming south in October and November, then a return to the north in late February and March. And we’re all quite aware of the occurrence of large gatherings of some of these migrants while they make stopovers on some of our largest lentic (still) waters—the man-made lakes and reservoirs created by damming local streams. But did you know that there are populations of colorful waterfowl with dynamic migrations that extend throughout the winter and early spring with movements that are often continuous. Under favorable conditions, these birds favor the lotic (flowing) waters of the river and its larger tributaries as they transit the lower Susquehanna valley. That’s because unpolluted lotic freshwater ecosystems support a greater diversity of plants and animals than lentic waters, and therefore offer more opportunities for hungry migrating waterfowl to find food. Let’s have a look at some of the species that visit the river during their seasonal journeys…

Ice on the Susquehanna — While the urge to head south in the autumn is largely stimulated by the shortening of the photoperiod, it is the presence of ice, particularly on glacial lakes throughout the lands to the north of the lower Susquehanna River basin, that pushes many diving ducks to finally make their way south toward the guarantee of open-water feeding areas along the coast. This movement may occur at anytime between November and late February or, as we have seen during some of the mild winters of recent decades, it may scarcely be noticed at all.

Common Mergansers often lead they way when it comes to migratory diving ducks. They regularly move south in conspicuous numbers by late November and December and are regularly pushing north as soon as the ice begins to melt. During a typical year, it is not unusual for some populations of these large diving birds to remain north of us during the winter. Then, in the days after a sudden rush of frigid polar air, an appreciable increase in ice cover will force a mid-winter movement of birds down the Susquehanna.

Heat Flux Sources Impacting Temperature in Lotic Fresh Waters — Temperatures in lotic fresh waters vary over the length of the stream or river. They are largely determined by the collective impact of the numerous sources of heat flux depicted in this graphic. (Environmental Protection Agency image)

Buffleheads begin passing through the lower Susquehanna region in Novemeber on their way to coastal saltwater bays for the winter. Lingering populations feed by diving in the river’s pools and riffles for benthic invertebrates including snails and insect larvae. Lesser quantities of aquatic plant matter supplement their diet.

Many Common Goldeneyes will remain on shallow, ice-free waters of the northern lakes and rivers sculpted by the most recent glacial event, but only until they are forced south into and through the lower Susquehanna valley by the encroachment of freezing conditions. On the river, they are among the dozen or so species of diving ducks we see visiting or passing through during the typical late fall and early river.

Geomorphological Zonation of a Stream or River — During their visits to the lotic (also known as riverine) fresh waters of the Susquehanna and its largest tributaries, benthic-feeding waterfowl make short dives to take advantage of the plants, small fish, invertebrates, and other food sources inhabiting the stream bottom in the riffles and pools of the free-flowing waterway. Substrates, listed here by size (in descending order), along with other parameters influenced by this flow regime zonation determine the variety and abundance of the forage available to migrating waterfowl and other consumers. Ice or high water and poor visibility due to flooding can render the riffles and pools of the channel unusable for feeding. The birds must then choose to either linger and rest without feeding or leave the lotic freshwater habitat to seek sustenance. During a flood, this may require relocation to a nearby lentic (still) body of fresh water such as a lake or reservoir. The presence of ice will almost invariably force the birds to fly on to the Atlantic Coastal Plain and the tidal waters of its bays and estuaries.

Hooded Mergansers are one of the few species of diving ducks likely to utilize flooded shoreline timber and riverine (fluvial) wetlands as refuge from high water on Susquehanna.

Pied-billed Grebe and Canvasbacks — A Pied-billed Grebe and a pair of Canvasbacks on an ice-free stretch of the lower Susquehanna in mid-winter feed and loaf in a riffle-flanked pool where a large mat of American Eelgrass, a submerged aquatic plant also known as Tapegrass or Wild Celery, grows during the summer. The vast mosaic of riffles and pools in a river this size offers tremendous opportunities for a diverse array of aquatic species to find their niche wherein they can survive and flourish.

The presence of ice forces Buffleheads and other diving ducks to gather in turbulent open water, often below a riffle or dam. Another alternative is to continue on toward the salty bays and estuaries of the coast. High water may push these birds into the shallows among the flooded woods to feed, but they seldom utilize heavily forested riparian wetlands as a refuge due to their need for a running start to get airborne.

**Riffle and Pool Characteristics of High Gradient (A) and Low Gradient (B) Streams**. This graphic illustrates the change in deposition characteristics of a stream or river as its gradient decreases. A high-gradient stream (A) has a rapid velocity, often forms falls, and tends to carry away a high volume of all but the largest of particles of potential substrates as they erode from the surrounding landscape. On a low-gradient stream, the loss in water velocity reduces the water column’s ability to transport even the smallest of substrate particles. Deposition of this gravel, sand, silt, and clay forms lateral bars that over time create the familiar meandering path of a naturally flowing lowland stream. (National Park Service image)

Benthic Life in Lotic Freshwaters — Benthic substrates in lotic freshwater pools and riffles support an abundance of life forms ranging from colorful diatoms on rocks and cobble, to invertebrates including snails and insect larvae, to fishes like this young Channel Catfish. Free of accumulations of sediment, this river bottom not only provides habitat for a healthy fishery, it facilitates the bidirectional exchange of water between the Susquehanna and its underlying aquifer.

On the lower Susquehanna, populations of young Quillback suckers are found almost exclusively in clear, high-gradient pools.

The Harlequin Duck winters along the rocky shores and man-made jetties of the Atlantic coast. In summer, they nest on fast-moving, headwater streams well to our north. Very rare on the Susquehanna, this is the first of two individuals found during March and April of 2025. It was observed feeding in the swift waters of the high-gradient riffles and pools where the river cuts through Blue Mountain north of Harrisburg. During previous weeks, Harlequin Ducks were being seen along the coast as far south as the mouth of the Chesapeake at Cape Charles, Virginia. It’s very possible that some of these birds traveled north through the bay area and up the Susquehanna on their way north.

**Fluvial Geomorphology of a Stream**. Many of the Susquehanna’s tributaries pass through each of these three erosional zones. Along the way, they carry out the process of breaking down the mountains formed by the Allegheny orogeny, the collision of North America and Africa that created the supercontinent Pangea about 325 to 260 million years ago (during portions of both the Carboniferous and Permian periods). Today’s main stem of the lower Susquehanna passes through a transfer zone (Zone 2), carrying eroded materials to a depositional zone (Zone 3) located within the ancient Susquehanna canyon stretching from Havre de Grace, Maryland, to Norfolk Canyon on the edge of the continental shelf. Within this zone, more than a 10,000-year accumulation of post-glacial sediments lies submerged by the rising waters of the Atlantic Ocean and Chesapeake Bay. Although the present-day lower Susquehanna is largely a transfer zone, some deposition occurs along low-gradient segments of the river, particularly where its course parallels the watershed’s ridges both above and below the high-gradient rapids where its path has eroded passage through the highlands. (National Park Service image)

Although the present-day lower Susquehanna is largely a transfer zone, some deposition occurs along low-gradient segments of the river, particularly where its course parallels the watershed’s ridges both above and below the high-gradient rapids where its path continues to erode passage through the bedrock. On this 1908 map of the Susquehanna at Conewago Falls, alluvial terraces of gravel, sand, silt, and clay can readily been seen as pale areas nearly lacking brown contour lines along the shorelines and islands of the river. Deposits within most of these terraces date back to the melt period following the most recent glacial event and beyond. The delta shown at the mouth of Conewago Creek (west) includes massive volumes of material deposited by both the creek and the river. This delta is currently known as Brunner Island, much of it developed as the site of a coal/gas-fired electric generating station. Terrace deposits along the Susquehanna’s shorelines created extensive perched marshes and swamps (wooded marshes) fed by rains, high river water, small streams, and springs, the latter often seeping from the base of the rocky escarpments carved by the ancient Susquehanna and defining the present-day inland border of the floodplain. We call these sites “Alluvial Terrace Wetlands”. Few of these critical components of river morphology survive. Those not drained for farmland were obliterated by urbanization and canal, railroad, and highway construction. (United States Geological Survey base image: Middletown, PA, quadrangle, 1908)

Water Willow is a familiar emergent plant that colonizes lateral bars and other alluvial deposits in low-gradient segments of the Susquehanna.

Water Willow Roots — The fine roots of Water Willow collect sediment and absorb nutrients while creating dense cover for young fish and numerous species of invertebrates including the Virginian River Horn Snails seen here.

Prior to the nineteenth century, the low-gradient flow regime of the river both above and below the riffles at Chiques/Chickies Rock (lower right on map) created prime wildlife habitat. The natural accumulations of nutrients and substrates carried into and through the lotic waterway’s pools and riffles were cycled into an ideal growing medium for extensive mats of American Eelgrass and other aquatic plants. This underwater forest hosted a seemingly endless abundance of invertebrates and fishes (both resident and migratory)—supporting a variety of consumer species including various populations of humans. But soon after the mass clearing of much of the watershed’s land for farming and lumber, the mill ponds created by dams constructed on streams to power saw and grain mills became brimful with sediments eroded from the unprotected ground. During storm events, torrents of these sediments then flowed full bore toward the Susquehanna, and began accumulating in the low-gradient segments of the river.

Legacy Sediments — Sediments left behind after the removal of mill dams are known as legacy sediments. They disconnect the stream from its historic floodplain and riverine (fluvial) wetlands, thus intensifying the impact of high water in the surrounding landscape. As these nutrient-charged deposits wash away, they become a source of pollution in the waters of the Susquehanna and Chesapeake.

A mat of American Eelgrass growing in the flowing waters of the Susquehanna below Conewago Falls. Eelgrass and other submerged aquatic plants provide essential habitat for a wide variety of small fish and invertebrates while also consuming nutrients deposited in the cobble, gravel, and sand substrate of the river’s pools. Excess quantities of smaller particles of silt and clay can clog the substrate and thus inhibit the hyporheic exchange of water between the stream channel and the underlying aquifer, often diminishing the biomass and diversity of organisms inhabiting this benthic habitat. Buried in these life-choking sediments, the river bottom becomes inhospitable to growth of submerged aquatics including eelgrass.

This low-gradient stretch of the Susquehanna at Marietta flows parallel to the Chickies Quartzite “Hellam Hills” before making a sharp right turn to punch through the ridge as a series of rapids at Chiques Rock. Formerly a fully functional lotic ecosystem and a paradise for migrating waterfowl, this river segment is now impaired by accumulations of nutrient-laden sediments from agricultural and urban runoff.

Conewago Falls Flood Waters — Nutrient and sediment-loaded flood waters roar across the diabase boulders at the York Haven Dam and Conewago Falls, a high-gradient segment of the Susquehanna.

Flood Waters at Haldeman Riffles — They continue past Brunner Island (left power plant stacks) and through Haldeman Riffles and the Shocks Mills Railroad Bridge…

Flooding on the Marietta Broads — …into the stretch of river known as the “Marietta broads” along the base of the Chickies Quartzite “Hellam Hills”. The low stream gradient here produces a slower current and increased deposition of sediments.

Susquehanna Flooding at Chiques Rock — As the flood surges through the riffle and pool complex at Chiques Rock, the high stream gradient maintains a velocity in the water column sufficient to keep additional sediments in suspension until they reach the low-gradient river segment just downstream at Washington Boro, site of a naturally occurring lateral bar area known as the Conejohela Flats. These bars now lie within the man-made depositional zone known as “Lake Clarke”. Created nearly a century ago by construction of the Safe Harbor Dam, this impoundment is accumulating astounding volumes of nutrient-loaded sediments that continue to encapsulate the flats within a stream-impairing delta.

Redheads, Canvasbacks, and a Horned Grebe — Anytime from November to April on the lower Susquehanna, a group of Redheads, Canvasbacks (3 birds to right of the middle of the picture), and a Horned Grebe (lower left) is a welcome sight in a riverine pool known to have a summertime growth of American Eelgrass. Noted Dr. Herbert Beck in 1924 when describing the Canvasback, “Like all ducks, …, it stops to feed within the county (Lancaster) less frequently than formerly, principally because the vast beds of wild celery which existed earlier on broads of the Susquehanna, as at Marietta and Washington Borough, have now been almost entirely wiped out by sedimentation of culm. Prior to 1875 the four or five square miles of quiet water off Marietta were often as abundantly spread with wild fowl as the Susquehanna Flats are now. Sometimes there were as many as 500,000 ducks of various kinds on the Marietta broad at one time.”

Aythya genus ducks. — Today, seeing just dozens of Aythya genus ducks (Redheads, Canvasbacks, scaup) on the lower Susquehanna is a notable event. If they happen to be forced down by inclement weather while migrating through, you might get lucky enough to see several hundred.

During the past two centuries, as food supplies in the Susquehanna grew increasingly compromised for benthic feeders like these Lesser Scaup and other diving ducks, a change in distribution was necessary for survival.

Lesser Scaup in flight. — As individual species, Lesser Scaup and other waterfowl that fail to adapt to natural or man-made changes in their habitats and food supplies may see their overall global numbers falter.

Despite being located in the transfer zone, the lower Susquehanna has become a significant depositional zone along much of its length, mostly courtesy of the placement of sediment-trapping man-made dams.

Following construction of the mill dams and ponds on nearly every mile of the lower Susquehanna’s low-gradient tributary streams, enterprising parties moved on to the river. The first significant spans were constructed using wide timber cribs filled with large rock. They were placed to create water deep enough to allow canal boats to cross the Susquehanna at both Clark’s Ferry at the mouth of the Juniata River in Dauphin County and at Columbia/Wrightsville. These dams also diverted water into the newly excavated canals—the Pennsylvania Eastern Division Canal (completed in 1833) which followed the river’s east shore from Clark’s Ferry to Columbia, and the Susquehanna and Tidewater Canal (completed in 1840) along the west shore from Wrightsville to Havre de Grace, Maryland. Placement of these sediment-trapping man-made dams began a process of converting vast mileage of the lower Susquehanna from a transfer zone into a deposition zone. In addition, layout of the canals and locks followed the contours along the base of the riverside ridges, seriously altering most of the alluvial terrace wetlands that the river had created as a feature of its floodplain during the post-glacial period.

Construction of the canal dams was just the beginning. During the twentieth century, more massive dams would be added to the main stem of the river for hydroelectric energy production at York Haven, Safe Harbor, Holtwood, and Conowingo. Upon their completion, the days of unassisted anadromous fish migrations were over. On both the river and its tributaries, smaller dams including dangerous low-head dams maintain water levels for boating and recreation. They too create current-diminishing, pseudo-lentic waters that blanket the lotic riffle and pool substrates with polluted sediments.

MAN-MADE DAMS TURN LOTIC WATERS INTO UNFLUSHED TOILETS

Sediment Deposition Behind Lower Susquehanna Dams — The construction of dams on the lower Susquehanna has converted vast mileage of the river from a lotic freshwater system into a series of man-made lentic freshwater reservoirs. These areas have lost their function as a lotic transfer zone and are now a sort of dysfunctional series of depositional zones collecting vast volumes of sediment containing nutrients and other pollutants. Within each impoundment, the reduced velocity of the river causes it to drop suspended sand first, then the finer particles of silt and clay closer to the dam. The flow regime of riffles and pools is lost and the hyporheic zone that exchanges water between the river and the underlying aquifer is clogged. These impaired segments of river become ripe for eutrophication: algal blooms followed by die offs that can lead to a fatal reduction of dissolved oxygen in the water column.

Deposits of lateral bars of sediment in low-gradient segments of the Susquehanna can create shallow water feeding habitat for puddle/dabbling ducks like these Gadwall. Where sediment pollution is severe, benthic foods in these areas often consist mostly of invertebrates and plant matter deposited by the current, the buried substrates devoid of a functioning ecosystem and the waters subject to eutrophication.

Common Goldeneyes on a patch of open water on an otherwise ice-covered “Lake Clarke”, the impoundment created by Safe Harbor Dam. While they may find this spot advantageous for loafing, the food supply over the sediment-buried substrate will be limited.

Dredging of sections of the lower Susquehanna for spilled, discarded, and washed-out anthracite coal sediment went on for nearly 100 years and was a particularly active enterprise in the Harrisburg area and in Lake Clarke until 1973. The recurrent substrate disturbances that accompanied waste coal recovery in these segments of the river repetitively damaged habitat for benthic life and may have been the catastrophic factor leading to the extirpation of two species of freshwater mussels: the Eastern Lampmussel (Lampsilis radiata) and the Dwarf Wedgemussel (Alasmidonta heterodon).

By the end of the twentieth century, accumulations of polluted sediments behind lower Susquehanna dams were nearing capacity. There is no working plan to attenuate the massive release of these pollutants that may be triggered by a catastrophic flood. The effort to reduce nutrient and sediment runoff remains the focus so that new loading is kept to a minimum and won’t add to the capacity problems at the dams or continue downriver to the Chesapeake at full strength when the dams are full. Alleviating the sediment aggregation problem within the river’s impoundments is a tall order and a dilemma not easily solved. (United States Geological Survey image)

Fortunately for everything else living in the benthos, Common Mergansers are big enough to devour invasive, non-native Rusty Crayfish when they find them in our lotic waterways.

TIME TO CLEAN UP OUR ACT

WHERE DOES YOUR STORMWATER GO?

Channelized Urban Stream — **Channelized Urban/Suburban Streams Function as Sewers.** They have no attached lowlands or floodplains to absorb, purify, and infiltrate runoff from rain events. Pollutants including litter, pet waste, lawn chemicals, tire-wear particles, hazardous fluids, and sometimes untreated human excrement flush unchecked from the municipal storm drainage system into the waterway. Thermal shock from summer downpours washing across sun-heated pavements can kill temperature sensitive fishes and other aquatic life. Nutrient and sediment loads from these impaired tributaries later accumulate downstream in low-gradient segments of the Susquehanna, turning the river into an open-air cesspool. Aggressively working to implement projects that eliminate these sources of pollution are the only effective way to keep the problem from getting worse. Making things better requires a lot more dedication and effort. (United States Geological Survey image by Frank Ippolito)

RIPARIAN BUFFERS MAKE A DIFFERENCE…WIDER IS BETTER

FLOODPLAIN RESTORATION

Regardless OF HOW LONG YOU’VE BEEN CONDITIONED TO THINK OTHERWISE, THIS IS A DYSFUNCTIONAL, POLLUTED CREEK—AND IT NEEDS HELP

RESTORED TO ITS HISTORIC FUNCTIONS

Floodplain and Stream Restoration — On an adjacent segment of the same creek, this legacy sediment removal project restored a braided meandering channel and connected it to its newly liberated, historic floodplain. In just their second year, the fluvial wetlands are effectively absorbing stormwater and sequestering nutrients as an attached component of the stream’s riffle and pool complex. During our visit earlier this week, we found American Toads, Northern Leopard Frogs (Lithobates pipiens), and Northern Spring Peepers breeding here. It’s just as Castor canadensis would have it!

“STOP HEMMING AND HAWING AROUND ALREADY”

“HEY COWBOY, HOW ‘BOUT GETTIN’ THEM FILTHY LITTLE DOGIES OUTTA DAT CRICK?”

Impaired Stream — Here’s a polluted stream in a pasture with grazing livestock. The site is a former mill pond within which the creek eroded a channel following removal of the dam. The animals defecate and urinate where access to water is gained at a broken down embankment of the nutrient-loaded legacy sediments deposited in the pond more than a century ago. It’s a haphazard form of animal husbandry and a reminder that all it takes is just one stubborn jackass to foul up the whole waterway.

DIRECT SOURCES OF NITROGEN (AMMONIA) POLLUTION IN STREAMS

DID YOU KNOW that a dairy cow produces about 80 pounds of waste (excrement and urine) every day?

DID YOU KNOW that a horse produces about 50 pounds of waste (excrement and urine) every day?

DID YOU KNOW that a human produces about 3 to 4 pounds of waste (excrement and urine) every day? The exceptions, of course, are those who continue to insist that raising farm animals in and alongside a body of water is okey-doke—a harmless practice. These individuals tend to retain the former constituent of human waste and are thus full of it.

“ATTABOY TEX, THAT’S MORE LIKE IT!”

Stream Fencing and Livestock Crossing — Now that’s better. Legacy sediments have been removed to reconnect the stream to its floodplain. A livestock crossing and exclusion fencing has been installed, and a nutrient-consuming riparian buffer has been planted. This creek segment’s pollution woes have been mitigated. Do you have a neighbor needing this type of remedial work on their farm? Encourage them to contact your local county conservation district office or volunteer waterways restoration organization for assistance. Various programs provide financial assistance covering all or most of the costs of stream improvement as well as monetary incentives for helping to clean up the water.

AND FINALLY

WHEN IT COMES TO BUILDING DAMS ON LOTIC FRESH WATERS…

…LEAVE IT TO THE BEAVERS

North American Beavers (Castor canadensis) create habitats that connect the riffle and pool regime of a low-gradient stream to a surrounding fluvial wetland that retains sediments, cycles nutrients, and provides essential habitat for hundreds of plant and animal species. Floodplains are for flooding, and if a beaver floods an area, you can be guaranteed that it was already part of a floodplain. You see, beavers don’t encroach upon humans, it’s humans engaging in the encroachment upon beavers. (National Park Service image)

MAD HATTERS

DID YOU KNOW that even before the landscape was cleared for farms and a supply of timber, and before mill dams on local creeks began accumulating soil runoff from the consequently barren hillsides, all the North American Beavers, the keystone species of lower Susquehanna stream ecology, were killed and sold to make hats? It’s no wonder things are fubar!

COMING SOON…

Horned Grebes are regular migrants and sometimes winter residents on ice-free stretches of the lower Susquehanna. They spend their time plying the benthic substrate of the river’s clear riffles and pools for a variety of invertebrates and small fish. Look for them moving north in coming days sporting this beautiful breeding plumage.

April and early May are prime time for observing Common Loons on the Susquehanna as they undertake a journey from the Atlantic surf where they spent the winter to nesting sites on northern lakes. For this migrant in breeding plumage, clear water for sighting plenty of benthic life in the river’s riffles and pools assures a successful dive in search of energy-replenishing forage.

December 21, 2025December 21, 2025

Photo of the Day

The first day of winter is the darkest day of the year. In the midst of the cold weather that accompanies it, one hardly thinks of looking for insect activity. But in subterranean environs where the temperature remains relatively constant, life goes on. We recently discovered this handsome Camel Cricket while performing some maintenance in our below-grade utility entrance. Worldwide in distribution, Camel Crickets, also known as Cave Crickets, Sand Treaders, and Spider Crickets, include hundreds of species in the family Rhaphidophoridae. Most are omnivorous residents of caves, mines, cellars, hollow logs, wood piles, wells, and other dark, temperature-stable situations where they feel their way around with their antennae while searching for food. Camel Crickets usually escape notice, keeping only nocturnal hours when venturing out from light-deprived cover and lacking the organs to produce the familiar “chirps” that call attention to other crickets during the breeding season.

November 24, 2025November 24, 2025

Photo of the Day

Among the last of the dragonflies to still be flying during late November is the Autumn Meadowhawk (Sympetrum vicinum). Earlier today, we photographed this specimen as it basked in warm sunshine at Wildwood Lake in Harrisburg. Elsewhere in the Lower Susquehanna River Watershed, look for Autumn Meadowhawks near lakes and ponds located within or near woodlands and forest.

November 5, 2025November 5, 2025

Photo of the Day

During these last mild evenings of fall, the trilling call of the Narrow-winged Tree Cricket (Oecanthus niveus) can still be heard among the withering growth of thickets, fields, and forest edges. As the temperatures plummet, the pulsating rate of this insect’s song slows proportionally. Below about 40 degrees Fahrenheit, there is silence.

October 18, 2025October 28, 2025

Robinson’s Invasion

As we begin the second half of October, frosty nights have put an end to choruses of annual cicadas in the lower Susquehanna valley. Though they are gone for yet another year, they are not forgotten. Here’s an update on one of our special finds in 2025.

During late June of 1863, the beginning of the third summer of the American Civil War, there was great consternation among the populous of the lower Susquehanna region. Hoping to bring about Union capitulation and an end to the conflict, General Robert E. Lee and his 70,000-man Army of Northern Virginia were marching north into the passes and valleys on the west side of the river. The uncontested Confederate advances posed an immediate threat to Pennsylvania’s capital in Harrisburg and cities to the east. Marching north in pursuit of Lee was the First Corps of the Army of the Potomac, the lead element of the 100,000-man Union force under the direction of newly appointed commander General George G. Meade.

Upon belatedly learning of Meade’s pursuit, Lee hastily ordered the widely separated corps of his army to concentrate on the crossroads town of Gettysburg. As the southern army’s Third Corps under General A. P. Hill approached Gettysburg from the west, they were met by Union cavalry under the leadership of General John Buford. Dismounted and formed up south to north across the Chambersburg Pike, Buford’s men held off Confederate infantry until relieved by the arrival of the Union First Corps. As he deployed his men, the First Corps’ commander, General John F. Reynolds of Lancaster, was struck by a bullet and killed.

General John C. Robinson Monument at Gettysburg — During the first day’s fighting at Gettysburg on July 1, 1863, the northernmost position in the Union First Corps’ line was held by its Second Division commanded by General John C. Robinson. His men would defend their right flank against attacks from Confederate General Richard S. Ewell’s Second Corps as they arrived from the north to face off against the Union Eleventh Corps which had arrived to take positions north of the town. During the afternoon, upon becoming outnumbered and overwhelmed, the Union forces would retreat south through the town to take up positions on Cemetery Hill by nightfall. Deployments extending south and east of Cemetery Hill would ultimately prove victorious for Union forces during the battle’s final day on July 3.

Lee's 1863 Invasion of the North — John C. Robinson’s Second Division “invaded” Pennsylvania as one of Meade’s lead elements charged with intercepting Lee’s Confederate Army. (National Park Service image)

If you visit the Gettysburg battlefield, you can find the General John C. Robinson monument at the site of his division’s first-day position along Doubleday Avenue at Robinson Avenue near the Eternal Light Peace Memorial. But that’s not the Robinson we went to Gettysburg to see.

Following up on our sight and mostly sound experiences with some Robinson’s Cicadas, an annual species of singing insect we found thriving at Gifford Pinchot State Park in York County, Pennsylvania, during late July, we spent some time searching out other locations where this native invader from the southern United States could be occurring in the Lower Susquehanna River Watershed.

During mid-August, we stumbled upon a population of Robinson’s Cicadas east of the Susquehanna in the Conewago Creek (east) watershed in Londonderry Township, Dauphin County, and made some sound recordings.

After pondering this latest discovery, we decided to investigate places with habitat characteristics similar to those at both the new Londonderry Township and the earlier Gifford Pinchot State Park locations—successional growth with extensive stands of Eastern Red Cedar on the Piedmont’s Triassic Gettysburg Formation “redbeds”. We headed south towards known populations of Robinson’s Cicadas in Virginia and Maryland to look for suitable sites within Pennsylvania that might bridge the range gap.

Our search was a rapid success. On State Game Lands 249 in the Conewago Creek (west) watershed in Adams County, we found Robinson’s Cicadas to be widespread.

Robinson's Cicada Habitat — Eastern Red Cedar, a probable host tree for Robinson’s Cicada nymphs, among successional growth on State Game Lands 249. Cedar thickets often become established on shallow or depleted soils on lands originally cleared for farming. They provide excellent cover as well as much needed breeding and feeding areas for birds, mammals, insects, and other wildlife.

Following our hunch that these lower Susquehanna Robinson’s Cicadas extended their range north through the cedar thickets of the Gettysburg Basin as opposed to hopping the Appalachians from a population reported to inhabit southwest Pennsylvania, we made our way to the battlefield and surrounding lands. We found Robinson’s Cicadas to be quite common and widespread in these areas, even occurring in the town of Gettysburg itself.

Robinson's Cicada Range in Central Pennsylvania — Populations of Robinson’s Cicadas (red) in the lower Susquehanna valley and adjacent areas of the Potomac watershed near Gettysburg. The Triassic Gettysburg Basin is shown in white with intrusions of igneous Triassic-Jurassic diabase in dark green. (United States Geological Survey base image)

Robinson's Cicada Habitat on Gettysburg Battlefield — Robinson’s Cicadas are common on much of the Gettysburg National Military Park property, particularly in the southern reaches where outlying areas are dense with Eastern Red Cedar growth to within several miles of the Mason-Dixon Line. In these tall walnuts and cedars along Confederate Avenue (that’s Little Round Top and its diabase boulders in the background) we recorded the following sound clip of a singing male.

Robinson’s Cicada probably extended its range into the lower Susquehanna valley in much the same way General John C. Robinson and the rest of the Army of the Potomac marched into Pennsylvania to meet Lee’s Confederates, by following the terrain of the Triassic Gettysburg Basin. Got a big stand of cedars near you? Be sure to have a listen for Robinson’s Cicadas next summer! (United States Geological Survey base image)

October 4, 2025

Photo of the Day

Peak time for the fall migration of Monarch butterflies is here. Look for them gliding by on gentle autumn breezes or feeding on nectar-rich flowers.

August 7, 2025August 7, 2025

Photo of the Day

A teneral Eastern Scissor Grinder and exuvia. — Having emerged from the soil overnight, this pale-colored teneral (soft-bodied) Eastern Scissor Grinder has shed its exuvia (left) and is currently pumping blood throughout its extremities to expand its size and unfurl its wings. During the remainder of the morning, the wings and exoskeleton will darken in color and harden in preparation for flight. As an adult, this cicada then has just weeks to complete its courtship and breeding cycle before facing inevitable doom. To see images and listen to sound clips of this and other annual species, visit our cicada page by clicking the “Cicadas” tab at the top of this page.

July 26, 2025October 18, 2025

A Sixth Species of Annual Cicada in the Lower Susquehanna Basin: Neotibicen robinsonianus

Just as we were very pleased last month to have the opportunity to hear the sounds of the rarest of the Periodical Cicadas—the Little Seventeen-year Cicada—in the Conewago Hills of York County to thus provide our only record of the species during the Brood XIV emergence in the Lower Susquehanna River Watershed, we were this week delighted to find and record a population of what may be the valley’s rarest cicada experiencing annual flights—the Robinson’s Cicada—just a few miles away at Gifford Pinchot State Park.

Like the Little Seventeen-year Cicada, Robinson’s Cicada (Neotibicen robinsonianus) is a species found more commonly in the southern United States, occurring with scattered distribution in a range that extends west into Missouri, Kansas, and Texas. They are of rare occurrence in the lands of the Chesapeake drainage basin in Virginia and Maryland.

Populations of Swamp Cicadas, also known as Morning Cicadas, are presently in the midst of their yearly courtship rituals. Their songs are easily heard in woods, edge habitat, and suburbia throughout the region during the AM hours. It was while recording the sounds of these common insects in the Conewago Day-use Area at Gifford Pinchot State Park that we noticed a very unique song from high in the oaks, hickories, and other hardwoods along the lake. Listen to this sound clip featuring a group of serenading male Swamp Cicadas. In the background, a Robinson’s Cicada’s song consisting of a pulsing series of raspy buzzes, each about one second in duration, can be heard, particularly starting at 00:40.

The Lower Susquehanna River Watershed, and Gifford Pinchot State Park in particular, may currently represent the northern limit of the geographic range of the Robinson’s Cicada. If you’re in the area during the coming weeks, drop by the park and have a listen. And don’t forget to check out our “Cicadas” page for sound clips of all the species found in our area.

July 21, 2025July 21, 2025

Sunny Swarms of Insects

It begins on a sunny morning in spring each year, just as the ground temperature reaches sixty degrees or more…

Eastern Subterranean Termites emerge in unison from a nest located in the soil beneath a log. Each of these swarming “alates” is a potential king or queen seeking to find a location with an ample supply of fallen timber to provide food for establishment of a new colony. They are escorted to the surface by a soldier (lower center) equipped with powerful jaws for protecting the existing nest. Similar-looking worker termites tend the nest, the queen, her eggs, and their siblings, but usually remain hidden from view. The workers feed upon wood, hosting cellulose-digesting protozoa and bacteria in their guts to break down the fibers. This symbiotic relationship is an important mode of decomposition in the forest, the process that turns wood into the organic matter that enriches soil and helps it to retain more moisture.

Fungi on Fallen Log — Termites are among the numerous arthropods that join fungi and a variety of microbes to decompose dead wood and other plant matter into the nutrients and organic materials used by living plants to thrive and grow.

Green Frog Stalking a Eastern Subterranean Termite — Soon after lift off, the majority of swarming termites are consumed by swallows, swifts, and other birds, but some are discovered at ground level.

Green Frog Eating Termites — A lightning-fast strike with its tongue and this Green frog has snatched up yet another termite. Those that slip by the dragnet of terrestrial and aerial predators can sometimes start a new colony in the ground beneath a dead tree or in a vulnerable house or other wooden structure. To keep a small clan from invading your home, be certain the wood elements of your building(s) are kept dry and are not in contact with dirt, soil, bark mulch, etc. Regular inspections for evidence of their presence can head off the long-term damage termites can inflict on the stuff we construct with tree skeletons.

Of course, termites aren’t the only groups of insects to swarm. As heated runoff from slow-moving thundershowers has increased stream temperatures during the past couple of weeks, there have occurred a number of seasonal mayfly “hatches” on the Susquehanna and its tributaries. These “hatches” are actually the nuptial flights of newly emerged imago and adult mayflies. The most conspicuous of these is the Great Brown Drake.

Seen here with a much smaller and more typical regional mayfly to its left, the Great Brown Drake was for several years infamous for swarming the lights and creating traffic hazards on bridges spanning the Susquehanna. During the past two weeks, nighttime flights of these giants have ventured out to gather at well lit locations in housing and business districts more than a dozen miles from the river. Earlier this century, this proclivity to wander probably led the Great Brown Drake to first invade silty segments of the Susquehanna as a colonizer from its native range in the Mississippi watershed.

Swarms of another storm-related visitor are being seen throughout the lower Susquehanna valley right now. Have you noticed the Wandering Gliders?

Throughout the month, swarms of Wandering Gliders, the most widespread dragonflies in the world, descended on areas hit by localized slow-moving thundershowers. Large numbers of these global travelers are known to get swept up within the thermal air masses that lead to these storms. In suitable terrain within the path of the downpours, they linger to search for flooded places where they can mate and deposit eggs. Wandering Gliders frequently mistake large parking lots at shopping malls, grocery stores, etc. for wetlands and will be seen in these areas depositing eggs upon the hoods and roofs of shiny motor vehicles, surfaces which appear puddle-like in their eyes.

Mating Common Green Darners — More dragonfly swarms are yet to come. Adult Common Green Darners are presently in the Lower Susquehanna River Watershed mating and depositing eggs within vegetated ponds, lakes, and wetlands. Beginning in August, adult Common Green Darners and other migratory species including Black Saddlebags, Carolina Saddlebags, Wandering Gliders, and Twelve-spotted Skimmers will begin swarming as they feed on flying insects (including lots of mosquitos and gnats) and start working their way toward the Atlantic Coastal Plain. Along the barrier islands by September, concentrations of southbound dragonflies can reach the thousands, particularly at choke points like Cape May, New Jersey, and Cape Charles, Virginia. So be sure to keep an eye on the sky for swarms of dragonflies during coming weeks. And don’t forget to check out our “Damselflies and Dragonflies” page by clicking the tab at the top of this page.

July 11, 2025July 25, 2025

With Periodical Cicadas Gone, Here Come the Annual Cicadas…Right on Schedule!

Eastern Scissor Grinder — As the choruses of Brood XIV Periodical Cicadas fall silent for another seventeen years, the sounds of the more widespread annual Neotibicen cicadas are starting to be heard throughout the lower Susquehanna valley. These latter insects have a more abbreviated life cycle, spending just two to five years in the subterranean nymphal stage before appearing during mid-summer to breed. The emergence of these annual insects is not synchronized into broods, so some adults are found taking flight, singing, and mating every year. Over the centuries, male annual cicadas that emerged and commenced courtship songs earlier than July have certainly failed to successfully reproduce during Periodical Cicada years. So to avoid competition with the overwhelming drone of the seventeen-year cicadas that may emerge along with them, natural selection has delayed the maturation of the annual species until just after the periodicals have gone quiet. To see pictures and hear the sounds of our five (now 6 as of July 24th) species of annual cicadas, click the “Cicadas” tab at the top of this page.

July 6, 2025

Sorry, But We Have No Steamed Crabs Today

Earlier today, we collected some mint leaves from the garden to make a batch of iced tea. Just prior to plunging them into boiling water, we noticed this Goldenrod Crab Spider (Misumena vatia) hiding in the foliage.

June 28, 2025May 26, 2026

Brood XIV Periodical Cicada Wrap Up

While the heat and humidity of early summer blankets the region, Brood XIV Periodical Cicadas are wrapping up their courtship and breeding cycle for 2025. We’ve spent the past week visiting additional sites in and near the Lower Susquehanna River Watershed where their emergence is evident.

We begin in York County just to the west of the river and Conewago Falls in mostly forested terrain located just southeast of Gifford Pinchot State Park. Within this area, often called the Conewago Hills, a very localized population of cicadas could be heard in the woodlands surrounding the scattered homes along Bull Road. Despite the dominant drone of an abundance of singing Pharaoh Periodical Cicadas, we were able to hear and record the courtship song of a small number of the rare Little Seventeen-year Cicadas. Their lawn sprinkler-like pulsating songs help mate-seeking males penetrate the otherwise overwhelming chorus of the Pharaoh cicadas in the area.

The Little Seventeen-year Cicada’s (Magicicada septendecula) thorax is black between the eye and the origin of the wings. It is the rarest of the three species of seventeen-year cicadas.

From the Conewago Hills we moved northwest into the section of southern Cumberland County known as South Mountain. Here, Pharaoh Periodical Cicadas were widespread in ridgetop forests along the Appalachian Trail, particularly in the area extending from Long Mountain in the east through Mount Holly to forests south of King’s Gap Environmental Education Center in the west.

Pharaoh Periodical Cicadas along the Appalachian Trail on South Mountain, Cumberland County, Pennsylvania. Like the cicadas we visited last week on the east side of the Susquehanna, this population is surviving on lands with a history of timber harvest and charcoal production to fuel nearby iron furnaces during the nineteenth century.

While on South Mountain, we opted for a side trip into the neighboring Potomac watershed of Frederick County, Maryland, where these hills ascend to greater altitude and are known as the Blue Ridge Mountains, a name that sticks with them all the way through Shenandoah National Park, the Great Smoky Mountains, and to their southern terminus in northwestern Georgia. We found a fragmented emergence of Pharaoh Periodical Cicadas atop the Catoctin Mountain section of the Blue Ridge just above the remains of Catoctin Furnace, again on lands that had been timbered to make charcoal to fuel iron production prior to their protection as vast expanses of forest.

A Pharaoh Periodical Cicada on Catoctin Mountain near Catoctin Furnace south of Thurmont, Maryland. These cicadas are not part of a Brood XIV emergence, but are instead a population of Brood X (2021) stragglers.

Back in Pennsylvania, we’re on our way to the watersheds of the northernmost tributaries of the lower Susquehanna’s largest tributary, the Juniata River. There, we found Brood XIV cicadas more widespread and in larger numbers than occurred at previous sites. Both Pharaoh and Cassin’s Periodical Cicadas were seen and heard along Jack’s Mountain and the Kishacoquillas Creek north of Lewistown/Burnham in Mifflin County. To the north of the Kishacoquillas Valley and Stone Mountain in northernmost Huntingdon County, the choruses of the two species were again widespread, particularly along the forest edges in Greenwood Furnace State Park, Rothrock State Forest, and adjacent areas of the Standing Stone Creek watershed.

Tymbal on the male Pharaoh Periodical Cicada — A view of the sound-generating tymbal on a male Pharaoh Periodical Cicada at Greenwood Furnace State Park. Rapid vibration of the tymbals by a set of specialized muscles generates the distinctive calls and courtship songs of the various cicada species. When handled, these tymbals can produce a harsh “panic call”. This distress sound could startle a would-be predator and provide the cicada with an opportunity to escape.

Tymbal on a Cassin's Periodical Cicada — The sound organs comprised of ribbed tymbals and specialized muscles on the male Cassin’s Periodical Cicada generate a “panic call” as well as the distinctive calls and songs used to penetrate the droning choruses of the more numerous Pharaoh Periodical Cicadas with which it shares a seventeen-year flight.

Cassin's Periodical Cicadas — Using their specialized sound organs, Cassin’s Periodical Cicadas generate a courtship song that usually includes buzzy phrases and ticking notes (first sound clip). The buzzing and ticking helps the male Cassin’s cicada penetrate the songs of the more numerous Pharaoh Periodical Cicadas in the area (second sound clip). When synchronized into a chorus that surges in volume, the songs of Cassin’s Periodical Cicadas can overcome the overwhelming drone of the nearby Pharaoh cicadas (third sound clip).

Pharaoh Periodical Cicada Depositing Eggs — After mating and before the lives of these seventeen-year cicadas draw to a close, the females need to deposit their fertilized eggs into the small end twigs of suitable trees. On a small hawthorn tree (Cretaegus species) along the edge of the forest at Greenwood Furnace State Park, this Pharaoh Periodical Cicada is using her ovipositor to make a slit in a twig and place her eggs.

Cassin's Periodical Cicada Ovipositing — Simultaneously on the same little hawthorn tree, this female Cassin’s Periodical Cicada is depositing her fertilized eggs.

Within the last 48 hours, we visited one last location in the Lower Susquehanna River Watershed where Brood XIV Periodical Cicadas have emerged during 2025. In the anthracite coal country of Northumberland County, a flight of Pharaoh Periodical Cicadas is nearing its end. We found them to be quite abundant in forested areas of Zerbe Run between Big and Little Mountains around Trevorton and on the wooded slopes of Mahanoy Mountain south of nearby Shamokin. Line Mountain south of Gowen City had a substantial emergence as well.

Foliage with Evidence of Ovipositing — Brown leaves reveal the end twigs where female Pharaoh Periodical Cicadas have deposited eggs during the last several weeks. During July, the larvae will hatch and drop to the ground to start a new generation of Brood XIV cicadas. As subterranean nymphs, they’ll spend the coming seventeen years feeding on small amounts of xylem sap from tree roots. In 2042, during the next Brood XIV emergence, these nymphs will come to the surface and take flight as adults.

Dead Pharaoh Periodical Cicadas — Accumulations of deceased Pharaoh Periodical Cicadas on Line Mountain.

Fallen cicadas that show any sign of life are being snatched up by predators such as this Eastern Gartersnake (Thamnophis sirtalis sirtalis). Meanwhile, the remainder of the biomass is picked apart by scavengers or is left to reducers for breakdown into fertilizer and organic matter for the forest. Nothing goes to waste.

To chart our travels, we’ve put together this map plotting the occurrence of significant flights of Periodical Cicadas during the 2025 emergence. Unlike the more densely distributed Brood X cicadas of 2021, the range of Brood XIV insects is noticeably fragmented, even in areas that are forested. We found it interesting how frequently we found Brood XIV cicadas on lands used as sources of lumber to make charcoal for fueling nineteenth-century iron furnace operations.

The furnaces at Greenwood Furnace State Park required the daily cutting of one acre of timber to make enough charcoal to fuel the iron-making process. Did keeping thousands of acres in various stages of forest succession to supply the charcoal needs of these operations aid the survival of earlier generations of Periodical Cicadas on these lands? Or, after the furnaces converted to coal for fuel, did the preservation of many of these parcels as state, federal, and private forests allow the cicadas to find refuge from the widespread impacts of agriculture and expanding urbanization in adjacent lands? Maybe it’s a little of both. We always bear in mind that annual insects and other animals are more than one hundred generations removed from the negative or positive impacts of the early years of the industrial age, but only about ten generations have passed since populations of seventeen-year Periodical Cicadas were directly influenced by these factors. What do you think?

Well, that’s a wrap. Please don’t forget to check out our new Cicadas page by clicking the “Cicadas” tab at the top of this page. Soon after the Periodical Cicadas are gone, the annual cicadas will be emerging and our page can help you identify the five species found regularly in the lower Susquehanna valley. ‘Til next time, keep buzzing!

June 16, 2025June 20, 2025

Brood XIV Periodical Cicadas in the Lower Susquehanna River Watershed

Here are some sights and sounds from the ongoing emergence of Brood XIV Periodical Cicadas in the Lower Susquehanna River Watershed.

We begin in the easternmost spur of the lower basin where a sizeable emergence of cicadas can be seen and heard in the woodlands surrounding the headwaters of the Conestoga River in Berks County north of Morgantown. This flight extends east into Chester County and the French Creek drainage of the Schuylkill River watershed on State Game Lands 43 north of Elverson and consists of Pharaoh Periodical Cicadas (Magicicada septendecim), the most common species among 17-year broods.

Pharaoh Periodical Cicadas exuvia — Exuvia of a recently emerged Pharaoh Periodical Cicada.

Pharaoh Periodical Cicada singing — Soon after landing on a perch, a male Pharaoh Periodical Cicada will usually announce his presence by singing. It’s an attempt to quickly attract potential mates that may be in the vicinity.

Pharaoh Periodical Cicadas singing chorus — Gatherings of thousands of singing male Pharaoh Periodical Cicadas create a distinctive droning chorus.

Chestnut Oak Hosting Cicadas — After mating, female cicadas make slits in the end twigs of selected trees into which they lay their eggs. The process of egg-laying and larval emergence will usually wilt and kill end growth on the affected branches, causing little harm to healthy trees. It’s similar to the trim you might give to a bonsai plant to keep it stout and sturdy.

A deceased Pharaoh Periodical Cicada at the Fire Tower Parking Area at French Creek State Park. This specimen and a chorus on the hill’s forested south slope were the northeastern-most evidence of Brood XIV Periodical Cicadas we could find for the population cluster in portions of Berks, Chester, and Lancaster Counties around Morgantown.

Second-year Mississippi Kite Feeding on Cicadas — The abundance of Pharaoh Periodical Cicadas on State Game Lands 43 in Chester County has attracted numerous raptors, particularly wandering one-year-old birds that aren’t quite mature enough to nest. Among the sightings have been Red-tailed Hawks, Red-shouldered Hawks, Broad-winged Hawks, and at least three Mississippi Kites, a rarity on the Piedmont this far inland from the coastal plain. (See the post from June 5, 2021, for details on the occurrence of Mississippi Kites in northernmost Delaware during the Brood X emergence.)

From Route 82 north of Elverson to the west through the forested areas along Route 10 north of Morgantown and the Pennsylvania Turnpike, we found an abundance of Cassin’s Periodical Cicadas (Magicicada cassini) calling among the Pharaohs. This mix of Pharaoh and Cassin’s Periodical Cicadas extends west along the north side of the turnpike into Lancaster County and State Game Lands 52 on Black Creek north of Churchtown.

Cassin's Periodical Cicada — A Brood XIV Cassin’s Periodical Cicada at State Game Lands 52 is identified by the all-black margin between the eye and the wing root and…

Cassin's Periodical Cicadas singing chorus — To penetrate the sounds of the more common Pharaoh Periodical Cicadas, male Cassin’s Periodical Cicadas gather in large concentrations to generate a loud, oscillating chorus. Its surging volume will usually exceed that of the Pharaohs singing in the vicinity.

Cassin's Periodical Cicadas mating — The underside of copulating Cassin’s Periodical Cicadas.

Further west in Cornwall, Lebanon County, a Brood XIV emergence can be found on similar forested terrain: the Triassic hills of the Newark Basin—rich in iron ore and renowned for furnace operations during the eighteenth and nineteenth centuries. Pharaoh Periodical Cicadas were the only species heard among this population that extends from Route 72 east through the woodlands along Route 322 into the northern edge of State Game Lands 156 in Lancaster County.

On the west side of the Susquehanna, yet another isolated population of Brood XIV Periodical Cicadas can be found in Perry County, just south of Duncannon on State Game Lands 170 on the slopes of “Cove Mountain”, the canoe-shaped convergence of the western termini of Peters and Second Mountains.

Pharaoh Periodical Cicadas dominated this Perry County chorus,…

…but we did detect at least one Cassin’s Cicada trying to find a mate.

Not to say they aren’t present, but we have yet to detect the rarest species, Magicicada septendecula, the “Little Seventeen-year Cicada”, among the various populations of Brood XIV Periodical Cicadas emerging in the lower Susquehanna valley. For the coming two weeks or so until this brood is gone for another 17 years, the search continues.

For more on both annual and periodical cicada species in the Lower Susquehanna River Watershed, be sure to click the “Cicadas” tab at the top of this page!

June 12, 2025

Photo of the Day

Along a quiet forest road, a Great Spangled Fritillary visits Red Clover (Trifolium pratense) to feed on nectar.

June 4, 2025June 4, 2025

Soakin’ Up the Smoky Sun

With temperatures finally climbing to seasonable levels and with stormy sun filtering through the yellow-brown smoke coming our way courtesy of wildfires in Alberta and other parts of central Canada, we ventured out to see what might be basking in our local star’s refracted rays…

Dragonflies including this Black Saddlebags are now actively patrolling the edges of waterways and wetlands for prey and mates.

Here we see a pair of Common Green Darners flying in tandem…

A sunny day almost always brings out the reptiles, including these Painted Turtles…

and the invasive Red-eared Slider, a native transplant from the American midwest.

…but this one seems to be fascinated by something a lot smaller. Something like these juvenile Golden Shiners seen here schooling in the sun-drenched shallows.

Turtles aren’t the only reptiles thriving in the heat. Northern Water Snakes (Nerodia sipedon sipedon) take full advantage of a sun-drenched rock to warm up after spending time in the chilly water of a stream.

Butterflies like this Spicebush Swallowtail enjoy time in the sun, even while seeking out minerals in a patch of moist soil.

Woodchucks — After its siblings darted into the familial burrow upon our approach, this juvenile Woodchuck instead sought the attention of its nurturing mother. Unlike its brothers and sisters, perhaps this little groundhog isn’t afraid of its own shadow. Or does the smoky haze have the youngster all confused about what does and doesn’t constitute as a shadow? Well, we can’t help you there, but you have a whole eight months to figure it out!

June 3, 2025June 12, 2025

Brood XIV Periodical Cicada Emergence

Its been four years to the day since we posted our account of the big Brood X Periodical Cicada flight of 2021 in the Lower Susquehanna River Watershed. With the Brood XIV clan of 17-year Periodical Cicadas getting ready fill the June air with their choruses in scattered parts of Pennsylvania’s Berks, Centre, Clinton, Franklin, Huntingdon, Juniata, Lancaster, Mifflin, Perry, Schuylkill, Snyder, Union, and York Counties right now, we thought it an appropriate time to open a new “Cicada” page here on the website. Included is a list of both the annually and periodically emerging species found in the lower Susquehanna valley, as well as a copy of the article and ID photos from the 2021 occurrence of Brood X. In coming months, we’ll be adding photos and maybe some sound clips of the different annual cicadas as well, so remember to check back from time to time for more content.

Periodical Cicada Nymph — Note the wings and red eyes of this periodical cicada nymph. Within weeks it will join billions of others in a brief adult emergence to fly, mate, and then die.

In the short term, we’re going to pay a visit to the Brood XIV territory and will bring you updates as we get them. Until then, be sure to click the new “Cicadas” tab at the top of this page to brush up on your ID of the three species of 17-year Periodical Cicadas.

Adult Periodical Cicada — Not to worry. Cicadas are native, harmless, docile creatures when handled and they pose no threat to the long-term health of your healthy, well-established trees and other vegetation, so enjoy them while they’re here!