Project Silk Moth
by Mary Thill
They have only seven days to live. Not enough time even to eat. And some of them spend their last nights on earth in the glare of a mercury-vapor light.
Pistachio-green, long-tailed luna moths with a wingspan nearly the size of my hand have been sitting on the sides of stores, schools and other overlit buildings every night for the past week in Saranac Lake. They are drawn to the white-blue glow of artificial light, sometimes lingering past sunrise, when they make easy prey for birds.
The luna moth is pastel-bright and unlike the mostly bark-colored creatures of the Northeastern woods. Mid-May to mid-July it emerges from a cocoon it spun as a caterpillar last year, then it has a week to mate, lay eggs and die.
Lunas are members of the Lepidoptera family Saturniidae, the giant silk moths. They are large and strikingly patterned, and most of them fly at night. The ranges of an estimated 10 types of giant silk moths overlap in the Adirondacks, mainly luna (Actias luna), cecropia (Hyalophora cecropia), polyphemus (Antheraea polyphemus), rosy maple (Dryocampa rubicunda), imperial (Eacles imperialis) and io (Automeris io).
If you see any of these or six other species, Janet Mihuc wants to know. Two years ago the entomologist, who teaches at Paul Smith’s College, began Project Silk Moth, a citizen survey intended to document where the lovely creatures are found in northern New York.
“The project focuses on [silk moths] because it is uncertain whether they are still declining (because of light pollution and the introduced parasitic fly) and because they are easy to identify so citizen scientists can contribute to the sightings database,” Mihuc e-mailed. “In the long run, the data will probably tell me more about distribution than abundance.”
This year Project Silk Moth is accepting reports until Saturday, June 30; submit sightings via the website. [Update: Mihuc says she will accept reports until July 31.]
Mihuc says the study hasn’t produced enough data yet to reveal patterns, but she has received verified sightings of the Columbia moth, a boreal species that had not been documented in New York State for several years. One sighting was at the Wild Center, in Tupper Lake. The museum then collected eggs a female laid on a branch, Dr. Mihuc hatched and raised the caterpillars, and the Wild Center will release them on its property this summer.
Although giant silk moths are not considered true silk moths (Bombyx mori), there have been efforts to domesticate them and create an American silk industry. In the mid-1800s, Etienne Leopold Trouvelot, a naturalist and entrepreneur living near Boston, experimented with several native moths. Sue Hubbell writes in Broadsides from the Other Orders, “He had studied the big, pale-green luna, the prometheus, and the eye-spotted cecropia, but by 1860 he had settled on what he and others called ‘the American silkworm,’ the polyphemus. Although the polyphemus was considered difficult to raise in captivity, its caterpillar did spin itself a cocoon, and the coarse threads it produced could be unreeled into commercial-grade silk.”
Trouvelot strung nets over a million polyphemus caterpillars on five acres behind his house, but birds got in and ate the larvae. He gave up, but not before trying imported gypsy moths, which quickly became defoliating pests. A parasitic fly was then imported to control gypsy moths; that fly is now believed to be killing native moths, an early failure of biological control.
Get Into the Field
If you’d like to see a giant silk moth, Sue Grimm, of the Butterfly House at the Paul Smith’s College VIC, had adult lunas and a cecropia as of Sunday; the prometheus and polyphemus moths there have died but their eggs and larvae promise more for next year.
The Wild Center, in Tupper Lake, has specimens in its Naturalist Cabinet as well as moths and butterflies flitting about its outdoor campus. A self-guided trail focused on butterflies will open July 4, for Buzzzfest 2012.
If you really want to get into moths, Mihuc recommends the new Peterson Field Guide to Moths of Northeastern North America. Start by looking near mercury-vapor lights. Or, to do moths a favor, turn your mercury-vapor light off.
Finally, to count all sorts of moths and animals and plants, the Adirondack All Taxa Biodiversity Inventory is holding a Bioblitz in Saranac Lake July 14–15. It will be a public event based at the Saranac Lake Free Library. To learn more, contact David Patrick at email@example.com, or visit the website.