Listener Lee in Enfield has a question for Something Wild:
"In the past few weeks I am seeing what I think are little moths flitting about. I have seen them both during the day but also at night. They are pale yellow. What are they still doing flitting about now that it is so cold? Shouldn't they be hunkered down for the winter by now? "
Something Wild co-host Dave Anderson of the Forest Society has noticed moths lately. “I assumed it was a function of the time I spend in the woods,” he says.
Co-host Grace McCulloch of NH Audubon says she’s been seeing them out on her walks as well. “They’re small — maybe an inch across — and they look totally out of place this time of year,” she says. “They’re a soft brown to gray, with this fluttery, kind of sluggish flight. Honestly, they look a little confused!”
These moths are sometimes called hunter's moths, from the adult male moth’s flight on cold autumn nights during hunting season.
They are formally Bruce spanworm moths (Operophtera bruceata).
They are adapted to cold weather flight through some metabolic adaptations. They spend the summer as caterpillars in the canopy of hardwood trees.
They eat and grow bigger until they fall down into the leaf litter and pupate.
As the weather turns cold, around the end of October, they emerge as adults. The advantage is that most insectivorous birds are now gone.
Only the males have wings; females are found crawling around on tree trunks and leaves.
The males seek out the flightless females via pheromones with chemo-receptor feathery antennae.
Bruce spanworm moths are native to New England.
They are very similar to “winter moths” which are an invasive moth of the same genus (Operophtera brumata). But even they get confused about the similarity and hybridize with each other.
The population experiences natural cycles. For example, in the early 1980s, high populations in New Hampshire and Maine caused extensive defoliation, with approximately 18,000 acres defoliated in New Hampshire during that period.
The name “Bruce” is a colloquial version of the species name “bruceata”. The species was named after an early lepidopterist.
The name “spanworm” (also called “looper,” or “inchworm”) refers to the characteristic crawling habit of this caterpillar and its relatives in the family Geometridae or “earth measurers”.
Caterpillars first stretch the front half of their bodies forward, then pull the back half of the body forward to meet the front legs, making a loop. As the front of the caterpillar stretches forward again, the body appears to span or “measure” a distance the length of their bodies.
If you have a question for Something Wild, email or send us a voicememo to SomethingWild@NHPR.org.
Something Wild is a partnership between the Forest Society, NH Audubon and NHPR.
