Friday, November 07, 2008

Mystery Moth

Recently, the Francis Beidler Forest Audubon Center received images from a visitor of a mystery moth...well, caterpillar. As the insect orders in Four Holes Swamp have not been as well-documented as plant and other animals species, we are always interested in identifying an insect, especially if we don't already have it on our list!

Images by Jeanne Seidler

The images of the caterpillar appear to be of a Luna Moth (Actias luna). Some suggested that it may also be a Polyphemus Moth (Anteraea polyphemus). However, according to the Caterpillars of North America (David L. Wagner), the Polyphemus Moth caterpillar has "flashy sliver and red warts," while the Luna Moth caterpillar has "bright magenta spotting and a weak subspiracular stripe on abdomen." Additionally, the Luna Moth caterpillar has a "anal proleg with dark band at its base that is inwardly edged with yellow, in a crude fashion resembing a head," while on the Polyphemus Moth caterpillar's "anal plate [is] continued as a line midway across A9." Finally, the Polyphemus Moth caterpillar has "steeply oblique yellow lines that pass through spiracles of A2-A7." The spiracles are the dots midway down the side of the caterpillar. Therefore, based on the color of the dots, the anal plate, and the lack of lines through the spiracles, we believe the mystery caterpillar is that of a Luna Moth.

Other caterpillar species are also busy preparing for the upcoming winter. One of today's 4th grade classes from Harleyville-Ridgeville Elementary School found a Pine Sphinx (Lapara coniferarum) caterpillar feeding around the heavily-forested parking area. Overwintering strategies include egg masses, silken cocoons attached to branches, silken cocoons wrapped in leaves, pupae burrowing into the soil, and adults seeking shelter in tree cavities or under bark. Here are some other caterpillar-related entries.

Image by Sarah Green

Can caterpillars like the Wooly Bear (Pyrrharctia isabella) predict the severity of the coming winter? "According to 'rural legend,' the width of the orange band can be used as a predictor of the severity of the coming winter, with narrower bands forecasting colder winters. In fact, the width is quite a variable character. At each molt, a protion of the black setae is replaced by orange, and hence the orange band is broadest in the last instar."

It's hard to think of winter on a day like today when the temperatures approached 80F!

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