this is the article I liked , but couldn't find ...
"A dark female Eastern Tiger Swallowtail mimics another butterfly called the Pipevine Swallowtail. Mimicry is when one animal looks just like another animal in order to gain safety or some other advantage. Pipevine Swallowtails eat a plant called Pipevine which makes them taste nasty to predators. Predators will learn to leave them alone. The dark female Eastern Tiger Swallowtail will also get left alone since it looks like a Pipevine Swallowtail, even though it is good to eat! Female tiger swallowtails will only have the dark form if a lot of Pipevine Swallowtails live in the same area. However, there will still be some light form females as well."
copied from -
http://www.fcps.edu/islandcree...
but this is also an odd statement because I see a lot of black Tiger STs but NO Pipevine STs here.
Although my county's local list of butterflies does include Pipevine STs.
