Erucism Due to Lepidoptera Caterpillar Envenomation
A 42-year-old woman contacted the Arizona Poison and Drug Information Center (AZPDIC) after envenomation by a tricolor buckmoth caterpillar (Hemileuca tricolor). She was underneath a mesquite tree in her yard when the caterpillar fell onto her posterior left shoulder. Within minutes, a pruritic urticarial eruption had developed. Within 1 hour after the envenomation, the patient took the accompanying photographs of the rash (Panel A) and of an identical caterpillar (Panel B) in her yard and sent them to the AZPDIC for recommendations. She was instructed to use cold compresses and topical antihistamine cream to alleviate her symptoms. The rash resolved within a few days. Erucism (also called caterpillar dermatitis) is caused by envenomation by the larval or pupal stages of moths or butterflies (order Lepidoptera). There are multiple venomous species in the United States and throughout the world, with the greatest concentration in the temperate and tropical climate zones. Rash is the most common clinical manifestation and responds well to antihistamines and topical glucocorticoids. However, allergic conjunctivitis or bronchospasm may occur if airborne hairs that are released from the caterpillar land in the person’s eyes or are inhaled. Anaphylactoid reactions have also been described.
