I saw a couple of hound's tongue (Cynoglossum officinale) plants and stopped to check for this species. Sure enough, there were at least 7 caterpillars of the confused haploa moth. This is a native species, but the plant on which its caterpillars are so often found, is not. When the caterpillars become disturbed, they thrash their bodies from side to side. The moths are a striking triangular shape with a distinctive brown and white pattern (which varies, hence the common name)!