Caterpillar Safety: Identifying Poisonous Species and Understanding Their Biology

Found caterpillars on the playground? Most are harmless. No hairless caterpillars are poisonous. Hairy or bristly ones—like tent caterpillars, woolly bears, and gypsy moth larvae—are rarely dangerous. Even horned species like tomato hornworms and hickory horned devils are safe.

The exceptions in Atlanta: the saddleback caterpillar (bright green with a brown saddle mark and stinging bristles at both ends) and the puss caterpillar (resembling a tiny fur ball, about quarter-sized, with venomous spines beneath the hairs). When in doubt, don't touch—ask an adult.

As for gender: caterpillars have undeveloped reproductive organs. Only after metamorphosis into butterflies or moths can sex be determined.