Lonomia Obliqua, Deadly Caterpillar

The genus Lonomia is a moderate-sized group of fairly cryptic saturniid moths from South America, famous not for the adults, but for their amazingly venomous caterpillars, which are responsible for a few deaths each year (e.g., ), especially in southern Brazil, and the subject of hundreds of published medical studies.
The caterpillars are themselves extremely cryptic, blending in against the bark of trees, where the larvae commonly aggregate. The larvae, like most hemileucines, are covered with urticating hairs, but these caterpillars possess a uniquely potent anticoagulant venom.