The Redbuds are full of these caterpillars, but their small size makes them hard to spot among the leaves. They’re all about a half inch long now and may grow to be three quarters of an inch before beginning the transformation into an adult moth.
The dorsal pattern looks to me like a diagram of the caterpillar’s digestive system with an arrow pointing the way out. The head is to the left in the picture. That brown object at the other end used to be leaf not too long ago.
Bright coloration is usually a warning for predators to keep their distance. In this case the warning pertains to needle-like spines that are capable of dispensing an irritant that causes itching and burning. You would have to have some very dull nerve endings to not feel the touch of this stinging caterpillar. I suppose it would be even worse for any small animal that messed around with this guy.
This individual was looking particularly brilliant, but on closer examination it appeared to be injured. Getting closer still, the cause of the deformity became clear.
The caterpillar had just shed and I was looking at the cast off skin. I wonder if those spines are still potent after they leave the caterpillar’s body.
The term slug caterpillar makes even more sense when you look at its under side. Waves traveling the length of that gelatinous belly provide locomotion very much like a slug or snail. The head is to the right, but is hidden within a fleshy hood. The hood provides protection to the head even while the caterpillar is feeding. If you decide to view a live slug caterpillar’s belly, I suggest you turn the creature over with a stick instead of your fingers. Feel free to ignore this advice if you like. It probably wouldn’t kill you.A Camera Critters submission.