Butterfly, Moth, and Caterpillar Envenomation

Excerpt

Lepidoptera is an order of insects that includes butterflies, moths, and caterpillars. Several caterpillars (the larval form of butterflies and moths) found worldwide contain spines or urticating hairs that secrete a toxin, irritating humans upon contact. Skin manifestations such as localized pain, edema, and erythema comprise most clinical presentations of Lepidoptera envenomation. However, some caterpillar species can cause severe injuries, including allergic reactions, consumptive coagulopathy, intracranial hemorrhage (ICH), acute kidney injury (AKI), ataxia, dysarthria, arthritis, joint deformities, wheezing, and dyspnea.

"Lepidopterism" (derived from the Greek words lepis, meaning scale, and pteron, meaning wing) refers to the various skin and systemic reactions secondary to human contact with moths and butterflies. "Erucism" (derived from the Latin word eruca, meaning caterpillar) refers to cutaneous dermatitis resulting from contact with caterpillars with urticating hairs.

More than 50 species of caterpillars are venomous in the US. The puss moth caterpillar (Megalopyge opercularis) is considered one of the most toxic in North America and causes hundreds of human envenomations annually. Other common names include asp, tree asp, Italian asp, wooly asp, opossum bug, wooly slug, and "el perrito." The puss caterpillar is found in the southeast and south-central US (particularly Texas, Louisiana, and Florida) and is abundant during the late spring (June-July) through the early fall season (September-October). The species is often found in trees and shrubbery around homes, schools, and parks. The typical physical characteristics include a teardrop-shaped furry body with silky tan to brownish hairs. Beneath this furry coat are short hollow spines attached to a venom sac that discharges upon contact. The color of the spines ranges from white, grey, tan, or yellow to reddish-brown.

Other notable venomous caterpillars in the US include the flannel moth (Megalopyge crispata), the lo moth (Automeris io), the saddleback moth (Acharia stimulata), and the hickory tiger moth (Lophocampa caryae). Lonomia obliqua caterpillars in South America, especially in Brazil, are infamous for causing severe pain and hemorrhagic syndrome. In Australia, caterpillars such as the mistletoe brown-tail moth (Euproctis edwardsi), processionary caterpillars (Ochrogaster lunifer), cup moths (Doratifera spp.), and the white-stemmed gum moth (Chelepteryx collesi) are of medical importance. Pine processionary caterpillars (Thaumetopoea pityocampa) are the important defoliator of pine forests in the Mediterranean and central European countries, with significant economic and occupational consequences for workers in these forests. The Anaphe venata caterpillar in Nigeria is an essential protein resource but can cause thiamine deficiency syndrome similar to dry beriberi. Additionally, dendrolimus caterpillars in China and Preolis semirufa caterpillars in Brazil are linked to significant joint disease.