Spring’s been racing along two to three weeks ahead of schedule: Bloodroot, Eastern Redbud and American Dogwood all bloomed early, followed by Star Chickweed and, by mid-April, Mayapple. Ladyslippers’ have been blooming for weeks under conifers in forested areas, and Cranesbill, or Wild Geranium, is now everywhere along the forest paths near my house. Ragwort is blooming in bright yellow waves in low, damp areas of the county and here and there in higher areas, and the white blooms of native raspberry and blackberry and the purple of wild phlox are appearing throughout the region.
Last week, to see how spring was progressing in the lower elevations of Shenandoah National Park, I loaded my dog into the car and headed up the hollow to Thornton River Trail, one of my favorite local spots for an easy but beautiful stroll through nature. Stepping onto the trail, I could see a small cloud of butterflies up ahead and, spotting fresh horse dung on the trail as well, I knew why the butterflies were there. While dung – or scat, as wildlife biologists prefer to call it – is not what most hikers go to the park to see, such deposits attract a wide variety insects, including diverse species of butterflies, flies, bees and wasps. The tiny critters take advantage of the nutrients and moisture that are made available through the donors’ digestion process.
A canid (dog, fox or coyote) had also left a deposit that was of particular interest to the insect gathering, which to my delight included a large dung beetle. I’ve been enchanted by large beetles since I was first hissed at by stag beetles in Germany, one of my first fond childhood memories. The dung beetle in question, a female most likely in the scarab-beetle family, was valiantly trying to extract a good-sized ball from the larger scat deposit so she could store it in her underground den for either her own use or to provide it as a nutrient source on which to deposit her eggs.
For a few minutes I watched the large beetle – shiny black and flat-headed – wrestle with her prize, but wanted to get further down the trail to a spot in the river suitable for my dog to soak away some of her arthritis discomfort. On the way back, about 20 minutes later, I stopped to see how the beetle had progressed in her task. She was still wrestling with the ball, working under and around it with little success at moving it to her burrow. I managed to get a few photographs to help with species identification later. Noting other insect species that were flitting around, briefly landing on the scat, I snapped a shot of a small, brownish butterfly before it took off again.
I kept stopping at every scat deposit on the trail to see the many species of woodland butterflies attracted to them, including a few species that were easy to identify, such as the tiny bright-blue Spring Azures and the much bigger Eastern Tiger Swallowtails (males in their yellow and black stripes and some females in black). Other smaller, quicker species in subtler shades of brown and gray flitted by: nymphs and other satyrs as well as skippers. I knew my camera was no match for these speedy little guys, but I did manage to capture shots of two brightly colored Zebra Swallowtails after a lot of patient waiting.
While adult butterflies find nutrition from several sources, they depend on plants to feed their caterpillars. In forested areas, trees are the most likely hosts. Eastern Tiger Swallowtails use a variety of host trees, but other butterfly species are obligated to just a few or even only one plant species. Zebra Swallowtails, for example, need Paw Paws, which are common in these lower, damper areas of the park, and Spicebush Swallowtail butterflies similarly need spicebush as hosts for their young.
When I got back home, I took a close look at the photos of the little brown butterfly I’d taken. In my brief look at it in the field, it had looked drab, but on my big monitor I could see small but lovely peach-colored triangles on the top of its wings, a subtle accent I’d missed that helped me with identification. Even then, I could only narrow it down to two similar skipper species in the same genus, the Mottled Duskywing (Erynnis martialis) or the Wild Indigo Duskywing (Erynnis baptisiae), named for one of its host plants.
I also started researching the dung beetle I’d photographed, although it was hard to get enough angles to be sure of the species. She was too busy digging under and around the ball of scat to try to gain command over it to model for me, and I didn’t want to disturb her work. Look for more about dung beetles, which are a lot more interesting and important to the environment than the casual observer might think, in an upcoming column.