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.

After completing this learning activity, participants should be able to recognize the most common species that cause caterpillar- and moth-related reactions, categorize the reactions based on the clinical manifestations, and choose the most appropriate therapy.