We just answered a regular reader’s question about the swallowtails we featured yesterday and thought perhaps we should show a comparison of all the swallowtails we happen to have photos of. We are by no means experts, and admit we have help from another reader–hi, Nancy!
The question was about the ‘dark phase’ being a Tiger Swallowtail. It is that same species, not a different one. The females are dimorphic, a biology term meaning they can have two forms, in this case, two colorations or phases. The scales that are normally yellow are a dark gray to black instead.
This should not be confused with Black Swallowtails, Pipevine Swallowtails and Spicebush Swallowtails, which are normally black. We should also point out that the dark phase here is an Eastern Tiger Swallowtail. From our research, we think it only occurs in the Eastern species. And, er, the the yellow ones we showed mineral sipping are Western Tiger Swallowtails. We were given those photos from our field correspondent in Colorado (remember Coney?) and actually didn’t put it together they were a different species. Sorry for any confusion that may have caused.
We won’t go into identification features here because it’s so complicated (which is why Nancy helps us) and there are better sites for that. We feel that if you know the possible names, you can look them up. So here we go with some comparison swallowtail photos, with names below the image!
Eastern Tiger Swallowtail
Western Tiger Swallowtail from Colorado. Note it does not have the blue above the ‘tails.’
dark phase Eastern Tiger Swallowtail
female Black Swallowtail
male Black Swallowtail
Pale Swallowtail – also a species from Colorado