I found these caterpillars on a Forest Pansy Red Bud tree, and they were also on a nearby Eastern Redbud, but I haven't seen them on any other plants or trees. They have a potent sting that left little red spots that seem to correspond to the yellow bumps down the dorsal black stripe. They have lots of hair-like projections from these nodules (somewhat visible in the closeup, out of focus photo). I'm just curious to know what they are -- the closest thing I've seen is Stinging Rose Caterpillar Moth (Parasa indetermina), but it doesn't really fit.