 Along the anterior, posterior and skirt of the caterpillar are tubercles that contain threatening hollow spines.While these spines are threatening alone, they actually go a step further in acting as a defense mechanism as they are connected to a gland that secretes venom that, when broken, is released into predators or unsuspecting gardeners.These spines are usually orange along the skirt of the caterpillar and orange or black along the tentacles present at both ends of the body.