The bioblitz I went to yesterday is for the Iowa Wildlife Center. It is a new wildlife rehabilitation center that will be located on previously farmed ground. There is some pretty good woodland on the area that probably has not been disturbed too much. There is a pond that was constructed with the intention of managing manure from a hog confinement (that fortunately was never built there). Behind the pond is a little wetland area which is loaded with swamp milkweed.
This giant swallowtail, Papilio cresphontes, was attracted to the swamp milkweed flowers. The giant swallowtail is our largest butterfly.
It seems to me that the nectar flows at certain times of the day. Milkweeds are extremely fragrant at times, and when you get the strong fragrance you will see all kinds of insects on the flowers.
I chased the giant swallowtail for a while. While I got some photos I liked I never got quite as close to it as I wanted. Then it flew away.