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Posts Tagged ‘female Eastern Tiger Swallowtail’

I love butterflies and am thrilled that I am finally beginning to see them more regularly after a slow start to this season. I spotted this beautiful female Eastern Tiger Swallowtail (Papilio glaucus) last week at Jackson Miles Abbott Wetland Refuge perched high in a patch of what looks like Joe Pye weed (Eutrochium purpureum).

Eastern Tiger Swallowtail

© Michael Q. Powell. All rights reserved.

 

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Most folks who live in the Eastern part of the United States can probably identify an Eastern Tiger Swallowtail butterfly (Papilio glaucus) when they see one. Eastern Tiger Swallowtails are large and have a distinctive pattern of bright yellow and black on their wings. However, not all Eastern Tiger Swallowtail butterflies are yellow—females come in two distinctly different variants, black and yellow.

The yellow morph looks a lot like a male, but with a conspicuous band of blue spots along the hindwings that the males do not have. The dark morph female has similar markings, but most of its body color is black, like the one below that I spotted last week at Green Spring Gardens. The perfect condition of its wings this late in the season suggests to me that this is a newly emerged butterfly.

So why do the females come in two colors? I read an interesting on-line article about this subject entitled “Why are you that color? The strange case of the dark phase tiger swallowtail.” The author speculates that the dark morph is an evolutionary attempt to mimic a similar-looking Pipevine Swallowtail butterfly that predators know is toxic, a practice known as Batesian mimicry. So, in theory the dark morph would have a better chance of survival. For unknown reasons, however, the males do not seem to be as attracted to the dark morph females, “These guys are apparently traditionalists and prefer the good ol’ yellow and black that their species is known for.” So the genes that might benefit species survival are not always passed on.

Eastern Tiger Swallowtail

© Michael Q. Powell. All rights reserved.

 

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