This species belongs to the family Limacodidae, a group of moths that are better known as caterpillars. They move with suction-cup feet and sort of glide along, and are therefore commonly known as "slug caterpillars." Nearly all of them can sting, even though their spines and hairs are not always noticeable. The stinging rose caterpillar is one of them, as is the spine oak slug. There are many othersm some of which have truly bizarre appearances.

 

For true spines, though, the saddleback caterpillar has them all beat. It has obvious spines, protruding from four fleshy tubercles. These spines bear a kind of venom that causes welts, pain and itching when touched. Stay away from the spines, and you'll be safe -- like all caterpillars, saddlebacks move slowly and cannot fling or launch their spines, or themselves, at you or anything else.

 

The moth of this interesting species is a pretty chocolate brown, often with tan and green markings. It is very seldom seen.