A Giant Among Swallowtails

The Giant Swallowtail (Papilio cresphontes) is a wonderful example of the obvious naming conventions among lepidopterans as it has swallow-tails and indeed is gigantic. 

Giant Swallowtails start life as a tiny, spherical orange egg laid on the newest and freshest growth of their host plants. From that tiny egg emerges a caterpillars that is equal parts remarkable and unusual.

The caterpillars do all their best to look shiny, wet, mottled and well, a whole lot like bird poop. In the world of insects there are a few ways to avoid being eaten: don’t be seen at all, be toxic, look like something toxic, look big, or look like something your predator already ate and discarded. It seems that birds are perfectly disinterested in further study of something they have already gotten rid of. This tactic, along with hosting on what I like to call “Unfriendly plants” (you know, the ones that are covered in spines and thorns) helps these caterpillars remain among the living.

The caterpillars also have a backup defense mechanism called osmeterium. Osmeterium are a fleshy organ where caterpillars of swallowtail species sequester essential oils from their host plants, also known as terpenes. These oils coat the normally hidden osmeterium which can be everted or pushed out when the caterpillar is threatened. The osmetierium are usually a bright warning color like red, yellow or orange and because of the terpenes smell quite foul. Have to move swallowtail caterpillars to new host plants also means that butterfly growers get their share of osmeterium love as the caterpillars arch backwards wildly, smearing predators faces and keepers hands alike with gross smelling oils. Each species has its own unique odor based upon what plants the caterpillar has been eating.

The adult butterflies are anywhere from 4 to 5.5 inches and wingspan and are bright yellow on their under-wings. Giant Swallowtails are a common sight throughout Florida as their host plants are abundant throughout the state. Giant females will deposit their eggs on the new growth of several types of tree in the citrus family and a few other species that are closely related to citrus. If you have a young citrus tree in your yard look for eggs to appear on the young, fresh leaves. Giants will host on lemon, lime, tangerine, orange, and sour orange just to name a few. Because of their taste for citrus, Giant Swallowtails are considered a minor agricultural pest in the state of Florida. The larvae are unlikely to truly defoliate their host plants and tend to not be much of a problem.

Giant Swallowtails also host on several Florida native trees that are closely related to citrus. Wild Lime (Zanthoxylum fagara) pictured to the left is also known as Cat’s Claw. The branches are covered in fine thorns that curve just like a cat claw. If you have ever had a run-in with a kitty, you probably know how uncomfortable those claws can be. Take care working around this plant as it tends to snag skin and clothing alike. However, as a Florida native it is well suited to our peculiar and temperamental climate and thrives in Tampa Bay gardens. In the MOSI gardens, Giant Swallowtails pass up nearby citrus and prefer to lay eggs on Wild Lime.

Hercules Club (Zanthoxylum clava-herculis) is another Florida native host. This tree has a spiky trunk and is often found in coastal areas. Ft. De Soto park has Hercules Club growing all over the site, including on top op the fort itself. Known also as Toothache Tree, a single leaf of Hercules Club when chewed and spit out can numb your entire mouth. That isn’t to say that it tastes great, because it certainly does not. 

So that’s the Tampa Bay story for the Giant Swallowtail, a butterfly that holds the impressive title of largest butterfly in North America