Thoas Swallowtail (Papilio thoas)
The swallowtails are among the easiest and most conspicuous of butterflies in Costa Rica, the Thoas Swallowtail being no exception to this rule. The combination of large size, bright colors, and preference for open, sunny habitats make this one a hard butterfly to miss even if you came to Costa Rica solely for river rafting.
The black and yellow swallowtails such as the Thoas Swallowtail have easily recognizable characteristics; large, pointed wing with long, narrow extensions on the lower wings. These are reminiscent of (and receive their name from) the tail feathers of a well known bird, the Barn Swallow. Although the black and yellow pattern of swallowtail species is also unmistakable, separating the Thoas Swallowtail from a few other similar species (especially the Giant Swallowtail) can be very difficult. Although most swallowtails probably won’t be identified to species, at least they are easy to see and fun to watch.
Behavior in Costa Rica
The Thoas Swallowtail is usually seen slowly opening and closing its wings as it feeds on nectar from flowers that grow along streams, and along the forest edge. In flight, it’s fast, maneuverable, and adept at avoiding capture by both birds and net-wielding butterfly enthusiasts. This species, like others of its kind, has evolved a remarkable strategy at avoiding predators during the larval stage. Instead of making use of irritating spines and hairs like other caterpillars, swallowtail larvae look exactly like bird droppings! When visiting one of Costa Rica’s national parks, if you think you see a bird dropping crawling on a leaf, you are not halucinating as you have probably just seen the caterpillar of a swallowtail butterfly.
Habitat and distribution in Costa Rica
The Thoas Swallowtail is a butterfly of lowland, humid forest edge and second growth. In Costa Rica, it is most common in regions that receive high amounts of rainfall such as the Caribbean, and south Pacific slopes.