What purpose do tails of swallowtail butterflies serve?

Asked July 6, 2013, 3:55 PM EDT

Has anyone ever definitively determined through experimentation that they serve any purpose, other than to suggest to humans a name for this group of butterflies? I know that they fly well without one tail, and without both tails.

Seminole County Florida

1 Response

Swallowtails are members of the family Papilionidae and not all members of that family even have the tails on their hind wings. We're used to seeing species like the tiger swallowtail with the tails, but the species in the family that are commonly known as birdwings do not.

I do not know of any studies that looked into how the tails might serve the butterflies in flight, but chances are they are just a byproduct of natural selection. Not every morphological feature on an organism is the result of positive selection. Some things (and the tails might be one of them) are just along for the evolutionary ride.