Friday, March 27, 2009

Woolly Bear

Yesterday I saw my first moth or butterfly (adult or larva) of the year. Yes, spring is very slow to arrive here; much of our yard is still covered in snow, some areas with several feet (sigh). But the woolly bear of yesterday brightened my spirits. He (or she) is such a welcome sight.

The woolly bear (Pyrrharctia isabella), also called the black-ended bear, is a common sight in the fall before first frost, but seen less often in spring. This lepidopteran bear overwintered somewhere in our yard, under leaves, bark, or logs. Now it is looking for a bit more to eat, before finding a spot to pupate and over time, hidden from view inside a fuzzy cocoon, transform into an adult Isabella tiger moth. The adult is a somewhat nondescript cream-colored moth, considerably less well known than its bear-like form, in part because moths are mostly active at night.

No one knows why the woolly bear crosses the road (which it is often seen doing in the fall). They are not particular about what they eat, consuming grasses, dandelions, lettuce, nettles, leaves of shrubs and trees. Probably they are dispersing to find a good overwintering site. The woolly bear curls into a ball as it overwinters and if it is picked up or disturbed plays dead, but quickly unfurling when left alone again.

The legend of the woolly bear is that the width of its center reddish-brown band, sandwiched between the two black ends, is a predictor of winter's severity. A narrow band forecasts a severe winter. All bunk of course, but still makes you look at the fuzzy little bear with a keen eye. In truth, at each molt, a portion of the caterpillar's black setae (the stiff bristles or hairs) are replaced by red-brown ones, so the middle band is widest in the last "instar" (or molt).

The folklore of the woolly bear as a predictor of winter's severity continues with festivals in parts of the country celebrating its forecasting prowess. How wonderful that people are enthused about a small woolly caterpillar. For me, seeing the woolly bear I know that spring is nigh, and that calls for a celebration.

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