Caterpillars and moths: Part II. Dermatologic manifestations of encounters with Lepidoptera.

Caterpillars and moths (order Lepidoptera) are uncommonly recognized causes of adverse cutaneous reactions, such as localized stings, papular dermatitis, and urticarial wheals. These reactions are typically mild and self-limited; however, in South America, the sting of Lonomia caterpillars can cause a potentially fatal hemorrhagic diathesis related to massive fibrinolysis. In addition, ocular inflammation and prominent arthralgias have been reported to be caused by caterpillar exposures. Therapies for mucocutaneous reactions to Lepidoptera are largely empiric, with the exception of antivenin against Lonomia obliqua envenomation. Part II of this two-part series on caterpillars and moths reviews the varied symptoms caused by Lepidopteran exposures, reviews the differential diagnosis, and discusses appropriate treatment algorithms.