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Spotlight

Giant Silk
Moth Survey

Perhaps you've come home late at night to find the porch light burning and a Luna Moth (Actias luna) clinging to the side of the house. Maybe you've paused to admire its dreamy green wings, feathered antennae and elegant shape. Now there's a new reason to look for Lunas and other giant silk moths.

Thanks to the suggestion of Jim Hedbor of the Vermont Entomological Society, we're adding giant silk moths to the project next year. It turns out that VBS volunteers can help understand the distribution and abundance of these charismatic moths. The largest and best-known of our moth species, they may also be in trouble.

Vermont has four known species of giant silk moths: Cecropia Silkmoth (Hyalophora cecropia), Promethea Silkmoth (Callosamia promethea), Polyphemus Silkmoth (Antheraea polyphemus) and the Luna Moth. Another species, known from Maine and Quebec, called the Columbia Silkmoth (Hyalophora columbia), may be found in Vermont as well.

The truth is that like many of the moths of Vermont, we know little about the locations and extent of giant silk moth populations. Unlike other areas of their range, populations in the Northeast have been in decline for years. One possible explanation is dispersal of the "natural" insecticide Bacillus thuringiensis (Bt) against gypsy moths. It most likely harms native insects as well. A recent study at the University of Massachusetts-Amherst seems to have found another culprit. Researchers there discovered that an introduced parasitic fly, Compsilura concinnata, attacks and kills giant silk moth caterpillars. The fly was repeatedly introduced from 1906 to 1986 to control some 13 pest species, including a related silk moth species. Concerns about the effect on native moths by this fly were expressed as early as 1919. We hope the addition of these moths to the Survey will help determine the conservation status of these incredible insects.

For more life history information and photographs of these species, visit the Moths of North America internet site via the links below:

Promethea silkmoth (Callosamia promethea)
Cecropia silkmoth (Hyalophora cecropia)
Polyphemus moth (Antheraea polyphemus)
Columbia silkmoth (Hyalophora columbia)
Luna moth (Actias luna)

Another informative site is http://www3.islandtelecom.com/~oehlkew/izsaturnos.htm.

If you want to get a start on finding these beautiful moths right now, learn about winter collection methods from the Michigan Entomological Society's Entomology Note No.9 - Collecting Giant Silkmoths.