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.
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 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.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.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.Like the others shown in our images, these may beetles were photographed after being attracted to man-made lighting. They’re frequently very noisy when tumbling in for a visit because their soft wing membranes, seen here protruding from the beetles’ posteriors, often tangle with their elytra, the hardened pair of front wings that make up over half of their armor-like dorsal surface when closed.A more colorful may beetle, aka Junebug.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.Skunks digging among grasses are often harvesting the larvae of many different species of scarab beetles.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.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.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.
The Broad-necked Root Borer (Prionus laticollis) is one of the Lower Susquehanna River Watershed’s largest insects. Its larvae feed on woody roots for more than two years before pupating and thereafter emerging as adult beetles. The distribution of root borers is not totally random. They are often attracted to distressed trees and shrubs. This particular specimen was found along a forest road where herbicide application, soil dehydration, and a recent wildfire has weakened and killed numerous oaks, poplars, and maples. As they feed, root borer larvae will help begin the process of reducing the remains of these trees into soil nutrients that will benefit regeneration of forest plants at this site.
It’s sprayed with herbicides. It’s mowed and mangled. It’s ground to shreds with noisy weed-trimmers. It’s scorned and maligned. It’s been targeted for elimination by some governments because it’s undesirable and “noxious”. And it has that four letter word in its name which dooms the fate of any plant that possesses it. It’s the Common Milkweed, and it’s the center of activity in our garden at this time of year. Yep, we said milk-WEED.
Now, you need to understand that our garden is small—less than 2,500 square feet. There is no lawn, and there will be no lawn. We’ll have nothing to do with the lawn nonsense. Those of you who know us, know that the lawn, or anything that looks like lawn, are through.
Anyway, most of the plants in the garden are native species. There are trees, numerous shrubs, some water features with aquatic plants, and filling the sunny margins is a mix of native grassland plants including Common Milkweed. The unusually wet growing season in 2018 has been very kind to these plants. They are still very green and lush. And the animals that rely on them are having a banner year. Have a look…
The flowers of the Common Milkweed were exceptionally fragrant this year. At their peak in early June, their hyacinth-or lilac-like aroma was so prevalent, it drifted into our building and overwhelmed the stink of the neighbor’s filthy dumpster that he had placed 12 feet away from our walls (100 feet from his).Common Milkweed attracts a pollinating Greenbottle Fly (Lucilia species). The dumpster attracts the invasive House Fly (Musca domestica), carrier of dysentery, typhoid, and other wonderful diseases. Are you following this? Remember as we proceed, milkweed is “noxious”.Busy Eastern Carpenter Bees (Xylocopa virginica) load up with pollen from the flowers of the Common Milkweed.A Red Milkweed Beetle (Tetraopes tetrophthalmus) munches on a tender fresh Common Milkweed leaf in mid-June.Following the pollination of the flowers, seed pods will begin to grow. We trim these off the plants. The removal of the extra weight allows most of the stems to remain erect through stormy weather. You’ll still get new plants from underground runners. As you may have guessed, we’re trying to keep these plants upright and strong to host Monarch butterfly larvae.
We’ve planted a variety of native grassland species to help support the milkweed structurally and to provide a more complete habitat for Monarch butterflies and other native insects. This year, these plants are exceptionally colorful for late-August due to the abundance of rain. The warm season grasses shown below are the four primary species found in the American tall-grass prairies and elsewhere.
Big Bluestem, a native warm-season grass in flower.Little Bluestem (Schizachyrium scoparium “Fort Indiantown Gap”) in flower. This variety grows on the tank range at the military base where the armored vehicles and prescribed burns substitute for the herd animals and fires of the prairie to prevent succession and allow it to thrive.Partridge Pea can tolerate sandy soil and is a host plant for vagrant Cloudless Sulphur butterflies.Black-eyed Susan (Rudbeckia hirta) is a popular native grassland wildflower.Indiangrass (Sorghastrum nutans) in flower. This and the other native plants shown here are available as seed from Ernst Seed Company in Meadville (PA). They have an unbelievably large selection of indigenous species. You can plant a small plot or acres and acres using really good mixes blended for purposes ranging from reclaiming pipeline right-of-ways and strip mines to naturalizing backyard gardens.A Red Admiral (Vanessa atalanta) butterfly, a migratory species like the Monarch, on Purple Coneflower (Echinacea purpurea). Yes, it is that Echinacea, the same one used as a supplement and home remedy.
There was Monarch activity in the garden today like we’ve never seen before—and it revolved around milkweed and the companion plants.
A female Monarch laying eggs on a Common Milkweed leaf.A third instar Monarch caterpillar with Oleander Aphids (Aphis nerii) on a Common Milkweed leaf. Both of these insect species absorb toxins from the milkweed which makes them distasteful to predators.Fifth instar (left and center) and fourth instar (right) monarch caterpillars devour a Common Milkweed leaf. There were over thirty of these caterpillars in just a ten by ten feet area this morning. We hope that if you’re keeping a habitat for Monarchs, you’re enjoying the same fortune right now!A slow-moving Monarch stopped for a break after making the circuit to deposit eggs on milkweed throughout the garden.Third instar (top), fourth instar (right), and fifth instar (left) Monarch caterpillars quickly consume the leaf of a Common Milkweed plant. Caterpillars emerging from eggs deposited today may not have sufficient late-season food to complete the larval segment of their life cycle. Need more milkweed!After benefiting from the nourishment of the Common Milkweed plant, a fifth instar Monarch caterpillar begins pupation on Big Bluestem grass.Two hours later, the chrysalis is complete.Another chrysalis, this one on flowering Switchgrass just two feet away from the previous one. An adult Monarch will emerge from this pupa to become part of what we hope will be the most populated southbound exodus for the species in over five years.There it is, soon ready to fly away. And all courtesy of the noxious milkweed.A chrysalis can often be found on man-made objects too. This one is on the rim of a flower pot.Ornamental flowers can attract adult Monarch butterflies seeking nectar. We’re now more careful to select seeds and plants that have not been treated with neonicotinoid insecticides. There’s growing concern over the impact these compounds may be having on pollinating species of animals. Oh…and we don’t mow, whack, cut, mutilate, or spray herbicides on our milkweed, but you probably figured that out already.
SOURCES
Eaton, Eric R., and Kenn Kaufman. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Company. New York.
