Caterpillar dermatitis.

Lepidopterism is the term used to describe the aggregate adverse medical effects resulting from contact with adult or larval forms of butterflies and moths. Histamine, histamine-releasing substances, kinin activators, and other as yet undefined proteins are responsible for cutaneous, cardiovascular, neurologic, and constitutional signs and symptoms of lepidopterism. Insect venom is likely injected into the skin through specialized caterpillar hairs when contact occurs with the insect (or vegetation laden with insect debris). Mild cases of lepidopterism will resolve spontaneously; systemic corticosteroids may aid in the treatment of more serious cases.