Monkey Slug

Yes, this is a Pennsylvania insect! Considered by some people to be the most distinctive caterpillar in eastern North America, the monkey slug (Phobetron pithecium) is the caterpillar of the hag moth. The hag moth is small and dark. The caterpillar is densely hairy with 3 long and 3 shorter pairs of lateral lobes armed with short urticating (stinging) spines. The lobes are deciduous, and hence occasionally missing.

Some people have speculated that to avoid predation, the monkey slug mimics the cast skins of other animals with urticating hairs. Their food source includes many forest trees and shrubs. The monkey slug can be found in its caterpillar stage from July to October.

The monkey slug has reduced thoracic legs, lacks abdominal legs (which are replaced by sucking discs), and moves in a creeping fashion. They are 0.4 to 1 inch long. The head is hidden under the thorax, and the body ranges in color from dull to bright (green, yellow, orange, red, brown and purple). This species is a member of the slug caterpillar moth family: Limacodidae. The caterpillars of species in this family all crawl with rippling gliding motion using their suckers. There are about 50 species in North America.

Today's photo is by Troy Bartlett @ bugguide.net.

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