Small green insect
One of our stinging slug caterpillars, possibly crowned slug, Isa textula, or a close relative. The little hairs arising from the lobes on the body of the caterpillar are stinging spines. Slug caterpillars of different stripes and colors can be found throughout the US. Some are rather colorful, but yours is fairly typical of the family (Limacodidae). Memorize its appearance and avoid touching them.