Cabbage White – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

May 25, 2025May 25, 2025

Late May Action in the Forest

Here’s a short preview of some of the finds you can expect during an outing in the Lower Susquehanna River Watershed’s forests this week…

The Mountain Laurel, designated as Pennsylvania’s state flower, is now in bloom.

Mountain Laurel Flower Buds — The buds of the Mountain Laurel remind us of a sugary frosting freshly squeezed from a baker’s pastry bag.

Mountain Laurel Flowers — The flowers of the Mountain Laurel, an evergreen understory shrub, invite pollinators to stop by for a sweet treat.

Little Wood-Satyrs (Megisto cymela) are patrolling forest edges looking for mates and, to host their eggs and larvae, the stands of grasses they find most suitable.

Many of the species of small butterflies we call skippers are now active. The Zabulon Skipper can be found patrolling grassy forest edges, particularly near streams, ponds, and wetlands.

Among the showiest of our butterflies, the Red-spotted Purple (Limenitis arthemis astyanax) is seen here on the leaves of a Black Cherry, its favored host plant.

Butterfly observers will do well to pay a visit to the new Susquehanna Riverlands State Park on Furnace Road north of Hellam in York County, Pennsylvania.

Trail to Schull's Rock Overlook — Upon arrival at Susquehanna Riverlands, drive back the gravel road for about a mile to the parking area at the edge of the agricultural field. Then, hike the trail through the woods and farm hedgerow to the Schull’s Rock overlook on the river. In the forests along this route, the understory is dominated by colonial stands of Common Pawpaw trees.

Along the lookout trail to Schull’s Rock, the Common Pawpaws’ large leaves help them to shade out potentially fast-growing competition. In proper growing situations, pawpaws develop clonal suckers that mature over time to create colonial stands of a single genetic plant.

Common Pawpaw understory. — A Common Pawpaw understory along the approach to Schull’s Rock.

During our recent visit to Schull’s Rock, dozens of Zebra Swallowtails were seen along the trail, many in the vicinity of their sole host plant, the Common Pawpaw. But even more were observed along the edges of the fields and woods where nectar sources like this Multiflora Rose were being visited by numbers of butterflies we normally see only among abundant species like Cabbage Whites. Absolutely amazing!

Scull's Rock Overlook — And the view of the Susquehanna and the Shock’s Mills railroad bridge at the mouth of Codorus Creek is pretty good too!

Common Pawpaw and Hooded Warbler — You can look for colonial stands of Common Pawpaw at other parks and preserves along the lower Susquehanna as well. Birds like this Hooded Warbler can sometimes be found among them in mature riparian forests along the steep slopes of the river gorge.

Common Pawpaw and Baltimore Oriole — A Baltimore Oriole in a Common Pawpaw along a forest edge.

Meanwhile in the treetops, the spring thrust of Neotropical migrants is drawing to a close. The Blackpoll Warbler is typically one of the last to transit the lower Susquehanna valley on its way to northern coniferous forests for summer. They’ve had an unusually protracted movement through the region this spring, the earliest individuals reported during late April. Though very difficult to see in the canopy of the mature trees where it feeds and sings, hearing one is often a benchmark for senior birders each spring. Older observers have often said of the Blackpoll Warbler’s high-pitched song, a rapid series of insect-like staccato “tseet” notes, that it was the first they could no longer detect as their ears started losing sensitivity.

In many tracts along the lower Susquehanna this spring, the American Redstart is turning out to be the most common nesting warbler. Conditions favoring their reproductive success in recent cycles, as well as good survival rates during their migrations and stays on wintering grounds, have filled many lowland forests with redstart songs in 2025. Is this the start of a trend or just an exceptionally good year? Time will tell.

Yet one more reason for a stroll in local forests this week is the chance to see and hear the Rose-breasted Grosbeak. Look for these Neotropical relatives of the cardinal nesting on territories in mature stands of deciduous trees like this Yellow Poplar, a species also known as the Tuliptree.

They spend nearly all their time among the canopy foliage of the largest timber…

July 27, 2024July 27, 2024

Wildflower Meadow Update

Do you recall our “Photo of the Day” from seven months ago…

Riverfront Park Wildflower Meadow — Here’s something to look forward to in the new year. The good citizens of East Donegal Township in Lancaster County have partnered with Alliance for the Chesapeake Bay to establish an extensive wildflower meadow on what had been a mowed field of turf grass at Riverside Park in the Susquehanna floodplain near Marietta. As the photo shows, the lawn plants have been eliminated in preparation for seeding with a diverse assortment of native grasses and wildflowers to provide habitat for birds and pollinators including butterflies, bees, and other insects. Once established, the meadow’s extensive vegetative growth will help reduce stormwater runoff by better infiltrating rainfall to recharge the aquifer. During flood events, the plantings will provide soil stabilization and increase the ability of the acreage to uptake nutrients, thus reducing the negative impact of major storms on the quality of water in the river and in Chesapeake Bay. Check the project’s progress by stopping by from time to time in 2024!

Well, here’s what that site looks like today…

And there are pollinating insects galore, most notably butterflies…

A Cabbage White collecting nectar on Blue Vervain.

A Sulphur — A Clouded or Orange Sulphur among the grasses in the meadow.

The Least Skipper is our tiniest butterfly.

The Little Glassywing (Vernia verna), this one feeding on vervain nectar, deposits its eggs on Purpletop grass, which then functions as the host plant for this butterfly’s larvae.

A Summer Azure (Celastrina neglecta) feeding on the nectar of a Black-eyed Susan.

A Common Buckeye on a “Gloriosa Daisy”, a showy, large-flowered cultivar of Black-eyed Susan.

A Red-winged Blackbird with a caterpillar found among the meadow’s lush growth.

An Eastern Tiger Swallowtail on Blue Vervain. Nearby Yellow (Tulip) Poplars and other trees serve as host plants for this butterfly’s larvae.

Black Morph Eastern Tiger Swallowtail — The black morph of the Eastern Tiger Swallowtail shows subdued shading in the wings that closely resembles the brilliant color patterns of the more familiar yellow form.

The Sachem, this one visiting a Black-eyed Susan, is a variable species with a range that normally lies south of the 40th parallel, the line of latitude that intersects the Susquehanna in the area of the Conejohela Flats at Washington Boro.

A Sachem visiting the blooms of Oxeye sunflower. During recent weeks, scorching winds from the south and southwest have transported an abundance of these vagrant skippers into the lower Susquehanna valley and beyond.

Here and there among the meadow’s plantings we noticed one of our favorites starting to flower, the Partridge Pea.

Partridge Pea happens to be a host plant for another vagrant from the south, the big, lime-yellow Cloudless Sulphur. We saw at least half a dozen patrolling the meadow.

Why on earth would anyone waste their time, energy, and money mowing grass when they could have this? Won’t you please consider committing graminicide this fall? That’s right, kill that lawn—at least the majority of it. Then visit the Ernst Seed website, buy some “Native Northeast Wildlflower Mix” and/or other blends, and get your meadow planted in time for the 2025 growing season. Just think of all the new kinds of native plants and animals you’ll be seeing. It could change your life as well as theirs.

A Snowberry Clearwing (Hemaris diffinis), more commonly known as a hummingbird moth, visits the flowers of Blue Vervain in the Riverfront Park wildflower meadow.

February 23, 2023February 24, 2023

These Geese are Outta Here!

Flies? Cabbage White butterflies? Can it really be a late-February day? It certainly is. Here are a few more signs of an early spring.

Green Frogs were out and about on this balmy February day trying to latch on to one of those flying insects. Their long winter’s nap lasted just over six weeks.

Approximately two hundred Common Grackles passed by susquehannawildlife.net headquarters today. This one stopped to have a look around before continuing its northbound expedition.

Migrating Canada Geese — Difficult to spot, hundreds of high-flying Canada Geese were seen in the hazy sky above the headquarters garden during the late morning. These migrants are working their way north from Chesapeake Bay and won’t be seen again in our region until fall.

August 21, 2017July 27, 2024

Beauties

It’s tough being good-looking and liked by so many. You’ve got to watch out, because popularity makes you a target. Others get jealous and begin a crusade to have you neutralized and removed from the spotlight. They’ll start digging to find your little weaknesses and flaws, then they’ll exploit them to destroy your reputation. Next thing you know, people look at you as some kind of hideous scoundrel.

Today, bright afternoon sunshine and a profusion of blooming wildflowers coaxed butterflies into action. It was one of those days when you don’t know where to look first.

A Pearl Crescent *(Phyciodes tharos)* sipping nectar from Rough Boneset *(Eupatorium pilosum)* flowers. Asters *(Aster)* are the host plants for the larvae of this butterfly.

A Common Buckeye *(Junonia coenia)* on Rough Boneset. Its caterpillars are known to feed on members of the Acanthus family, possibly including the Water Willow (Justicia americana) which is so abundant in Conewago Falls.

Visitors from south of the Mason-Dixon Line arrived on the recent warm winds. Two Cloudless Sulphurs *(Phoebis sennae)* patrolled the Riverine Grasslands, especially near the stands of Partridge Pea, a possible host plant. One is seen here visiting a Halbred-leaved Rose Mallow blossom. These large yellow butterflies are always a standout.

Purple Loosestrife (Lythrum salicaria) has a bad reputation. Not native to the Americas, this prolific seed producer began spreading aggressively into many wetlands following its introduction. It crowds out native plant species and can have a detrimental impact on other aquatic life. Stands of loosestrife in slow-moving waters can alter flows, trap sediment, and adversely modify the morphology of waterways. Expensive removal and biological control are often needed to protect critical habitat.

The dastardly Purple Loosestrife may have only two positive attributes. First, it’s a beautiful plant. And second, it’s popular; butterflies and other pollinators find it to be irresistible and go wild over the nectar.

A Silver-spotted Skipper *(Epargyreus clarus)* feeding on Purple Loosestrife nectar. The host plants for this common butterfly’s caterpillars are a wide variety of Legumes.

A Cabbage White *(Pieris rapae)*, a butterfly introduced from Europe in the 1800s, feeds on introduced Purple Loosestrife.

A Wild Indigo Duskywing (Erynnis baptisiae) feeding on Purple Loosestrife. This butterfly has expanded its population and range by using the introduced Crown Vetch as a host plant.

Don’t you just adore the wonderful butterflies. Everybody does. Just don’t tell anyone that they’re pollinating those dirty filthy no-good Purple Loosestrife plants.

SOURCES

Brock, Jim P., and Kenn Kaufman. 2003. Butterflies of North America. Houghton Mifflin Company. New York.

Newcomb, Lawrence. 1977. Newcomb’s Wildflower Guide. Little, Brown and Company. Boston, Massachusetts.