Saddleback caterpillar

The caterpillar is primarily green with brown at either end and a prominent white-ringed brown dot in the center which resembles a saddle. It has a pair of fleshy horns at either end. These and most of the rest of the body bear urticating hairs that secrete an irritating venom. Contact with the hairs causes a painful, swollen rash and sometimes nausea in humans.