Papilio thoas (Thoas swallowtail) occurs from southern Texas through Mexico, Central America, the Caribbean, and South America to Argentina and Uruguay. It is a large, fast-flying butterfly with dark narrow wings crossed by a broad cream-yellow band and a long tail on each hindwing. The pattern closely resembles the giant swallowtail, and careful attention to spot arrangement is often needed to separate them.

Adults visit flowers including lantana, bougainvillea, and other nectar sources, frequently beating their wings while feeding. Females place eggs on larval host plants in the citrus and pepper families. The caterpillar resembles bird droppings when young and later develops a larger mottled form with defensive eyespot-like markings. When disturbed it can extend a forked scent organ called an osmeterium. Photographed in Colombia.