Woolly bear

[HALISIDOTA MACULATA]

Chilly autumn mornings prompt a miniature migration of woolly bear caterpillars that slink along trails and fields in great numbers. Famed for their supposed ability to predict winter weather, these larvae of the tiger moth are in search of logs, rocks and piles of leaves under which they can sleep through cold winter months curled in a tight ball. Come spring, they’ll awake ravenous, ready to devour fresh leaves before spinning a cocoon with their long bristly hairs and reemerging as adult moths in late May. Woolly bears are particularly numerous around willows at lower elevations throughout California.

NATURAL HISTORY

The caterpillar’s bands grow in girth with each molt, so a cold early fall sends relatively young caterpillars with narrower bands in search of shelter. Woolly bears are simply responding to the seasons rather than predicting them.

KEY CHARACTERISTICS

Caterpillars are 2 inches long and black, with a pale band encircling their midsection and long white hairs extending from each end of their bodies.

Moths are yellowish-brown, with a slightly

darker marbling.