Some type of Peruvian HAG MOTH CATERPILLAR - Phobetron sp. (Lymacodidae)  © Rafael Oliveir

The hag moth larva, sometimes called the monkey slug, is distinctive in form and easy to identify. The full-grown caterpillar is brown, hairy, and about ⁵/8 inch long. Along the body there are nine pairs of fleshy lateral processes which bear hidden urticating setae. The third, fifth, and seventh pairs of processes are long and sometimes twisted. These have been described as resembling “disheveled locks of a hag”, apparently the basis for the common name.

The caterpillar is generally a solitary feeder, and will feed on foliage of several trees including apple, ash, birch, dogwood, hickory, oak, and willow.