'Puss' Caterpillar Sting

While doing yard work, a man experienced acute, severe, burning pain on relatively brief contact with the caterpillar Megalopyge opercularis. The lesion shown in the photograph developed subsequently. Each red papule represents the site of direct cutaneous envenomation by the insect's poisonous body hairs. The caterpillar can vary in color from white to dark brown, depending on the surroundings and time of year. The fuzzy hairs resemble a cat’s fur; hence the nickname “puss.”

A sting from this harmless-looking insect can result in severe muscle cramps, intense headache, tachycardia, respiratory distress, convulsions, and shock. This patient experienced paresthesias for nearly a week, but no other systemic manifestations. The area healed completely within 10 days. Treatment is symptomatic and supportive.