PHOTO COURTESY OF GARRY KESSLER
The question mark butterfly, with wings open, showing the top sides.
October 18, 2019, Page A4
By Annie Reid
Westborough Community Land Trust
Spotting butterflies in the fall
Fall butterflies? The notion seems improbable. Yet even in October and into November we can spot these “flowers that fly” (in the words of poet Robert Frost) in our area.
In September it’s easier to find butterflies. Did you notice monarchs on the wing, heading southward on their migration to Mexico? In fields or gardens, did you see cabbage whites, small yellow butterflies called clouded sulphurs, orange sulphurs, or others?
Would you believe that by October 7 of this year, Massachusetts Butterfly Club members had already collectively spotted 30 butterfly species in October? That’s out of slightly more than 100 butterfly species normally found in our state.
One interesting fall butterfly is the question mark (Polygonia interrogationis), which has had a pretty good year in Massachusetts. It’s medium-sized, with a wing span of 2-1/2 inches, and can usually be seen from March to November. The tops of its wings (seen when open) are orange with black spots. The undersides of its wings (seen when closed) are light to dark brown with a small white curved mark and dot which together resemble a question mark, giving this butterfly its name.
PHOTO COURTESY OF GARRY KESSLER
The question mark butterfly, with wings closed, showing the undersides.
How do question marks survive in early spring and in fall, when flowers are few so there’s not much nectar to sip? This butterfly’s trick is that it doesn’t often feed on nectar. Instead, it nourishes itself on tree sap, rotting fruit, and even dung. With this diet, it’s no surprise that the question mark is a woodland butterfly. Watch for it at woodland edges and openings.
What about winter survival – that great challenge for creatures (and plants) in New England? Different butterflies pass the winter in different life stages – as eggs, as caterpillars (larvae), as pupae inside a chrysalis, or as adults. Like monarchs, question marks overwinter as adult butterflies, and like monarchs, question marks survive New England winters by escaping them.
Most (but not all) question marks migrate southward in fall and northward in spring, but their migrations are not as dramatic or as far as the monarch’s. They move to places south of New York City (not to Mexico like the monarchs), where they may hibernate. And some question marks remain here and tuck themselves into cracks in bark and other crevices to hibernate for the winter. A question mark that you spot in spring might have just returned from parts farther south.
How do question marks “know” to migrate in the fall? Most likely, those that are in their caterpillar stage in late summer are affected by the shortening of days, which probably triggers genes that prepare them to migrate and to hibernate once they become adult butterflies. (Of course, the story is undoubtedly more complex than this short answer suggests.)
Speaking of caterpillars, what do question mark caterpillars eat? Their host plants are typically elm saplings, as well as hackberry, nettles, and hops (grown widely in Massachusetts for beer-making from colonial times to 1830 or so).
Keep your eyes open for question marks – and a near look-alike, the eastern comma (Polygonia comma) – and others. For photos of Massachusetts butterflies, check out the Massachusetts Butterfly Club web site.