It was never a good idea to bug Johan Christian Fabricius.
Fabricius was a Danish zoologist who specialized in insects and was way too busy for any mundane interruptions. In fact, he was considered one of the most important entomologists of the 18th century.
At one time a student of Carl Linnaeus, Fabricus eventually outshined the father of biological nomenclature after he named more than 10,000 species of insects and established an interesting basis for their classification. He postulated that “those whose nourishment and biology are the same, must then belong to the same genus,” and created a classification system based on insect mouthparts and therefore their foodstuffs.
Among the selections of species that he named was Cercyonis pegala. He chose the name to honor Cercyon, son of Poseidon, and “pegala,” suggesting a well or fountain. We know this creature as a common wood nymph butterfly.
It is hard to miss the common wood nymph, which is appearing in the fields, forests and marshes in large numbers. This is the medium-sized brown butterfly with two yellow ringed eyespots on their forewings that you likely have been noticing fluttering around in large numbers. Observe their bouncy flight, likely the reason for their common name.
Though common wood nymphs emerge in mid-May and can be seen into early October, the numbers we are seeing now are impressive. This butterfly has only one brood per year. Males are noticeable now, patrolling for females with their dipping flight pattern. They have only a short time to find a mate since the male lives only a few weeks. Females, however, will stick around for several months.
Their mating was described eloquently, if not scientifically, by a researcher: “the male pursues the female, who lands . . . and then remains motionless with her wings closed; the male then lands and flutters his wings at full stroke while butting her head with his head, his forewings drawn forward to transfer pheromone from his upper forewing (scent) patch; next he moves to her side and flutters his partly- opened wings with smaller strokes, and then bends his abdomen to mate.”
Common wood nymph eggs are laid primarily on grasses which are the larval food for the emerging caterpillar. Andropogon, purple top and cordgrass have been observed supporting these caterpillars, which do not eat when they first emerge. Green/yellow caterpillars with white hairs overwinter before taking a bite. Spring brings hunger and they will begin to eat and eventually metamorphose into a green chrysalis. The butterfly finally emerges in the summer.
As butterflies, they feed on nectar, tree sap and decaying matter. Common wood nymphs favor butterfly weed, thistles, wild carrot, teasel, wild bergamot, mountain mint, black eyed Susan, clover and ironweed for a sweet snack.
Although common wood nymph butterflies might not (except to an entomologist) possess all the beauty of the type of wood nymph celebrated by mythologists, artists and poets, it is possible to imagine Johan Christian Fabricius sharing Sir Walter Scott’s sentiments, as he contemplated the “fountain-like flyers” that he had named:
And ne’er did a Grecian chisel trace
A nymph, a naiad, or a grace,
Of finer form or lovelier face.
Suzan Bellincampi is director of the Felix Neck Wildlife Sanctuary in Edgartown.