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Writer's pictureJessica Morgan McAtee

Giant Swallowtail Butterflies are a Big Thing!

Updated: Sep 29

Giant Swallowtails (Papilio cresphontes) are among the largest butterflies we have in the US. Female wingspans can be upwards of six inches! They are found across the southern border states from southern California and Nevada to Florida. The entirety of the Northeast and Midwest states get them. Their range doesn't include the far north west states of Washington, Oregon, Nevada, Idaho, Utah, Montana or the Dakotas, but just about everyone else gets graced with these big beauties.


This post aims to give a brief life history of the Giant Swallowtail butterfly in photos.


They typically hibernate in their chrysalis over winter. However, in Florida and the deep south, they can be seen flying year round.


Giant Swallowtail adult in Florida

Like many American Swallowtails, they are mostly black and yellow. Males may have a dash of red and blue on the inside of their hindwings on the dorsal side but this can fade as they age. The easiest way to recognize them is the dorsal line of yellow spots that spans from one forewing to the other. When they are at rest, this appears to be a horizontal line, but in flight it's more of a V shape.


Giant Swallowtails are colorful on their ventral side too. Another feature is the yellow spot on the tails of their hind wings that can be seen from above or below.


Since they are so large, they rarely rest on flowers, but rather, flit over them as they nectar. In this photo it is nectaring on a Panama Rose.


Giant Swallowtail nectaring on Panama Rose

This big butterfly lays its eggs on trees in the citrus family. That means that its host plants have thorns, which isn't great if you have a small butterfly habitat and hope to attract them. The other challenge is that they host on trees, which require more space than something like a milkweed.






The female lays round eggs individually on the leaves of the host plant. A quirky characteristic of their caterpillars is they resemble bird droppings in every stage. They look glossy and wet and are brown and white.


This tiny Giant Swallowtail larva is smaller than a dime

As the caterpillars grow, they look like even bigger bird poops. However, they do have some beautiful blue flecks in them which is a nice artistic touch. I call it Blue en Poo.



Giant Swallowtail larva in later instar


Giant Swallowtail caterpillar looks like poop

Caterpillars in the broader Swallowtail family have another fun trick. They have a secret gland called an osmeterium that will emerge from just behind their head. In Giant Swallowtails, it sprays a nasty odor that lingers. This gland is not harmful to humans, it is just a ruse.





Like all Swallowtails, their pupa will attach in two places. One is the cremaster at the bottom and the other is a silk band around the mid-section.



A prepupal portrait of Giant Swallowtail larva


This butterfly will often pupate on the host tree. It's chrysalis resembles a broken twig and blends in fabulously with the bark.




Giant Swallowtail pupa looks like a twig

Up north, this butterfly will stay in its chrysalis over winter. Once temps are sufficient, it will emerge and start the cycle of life over again.


These butterflies aren't as common as some of the other garden visitors, so it is

a giant treat to have one fly into your habitat.


Its the little things

Jessica


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