Critters in my yard and nearby.

I know that the caterpillar became a black swallowtail butterfly and that Lucy likes studying the praying mantis outside the front window. But what is (are?) that (those?) flying insect(s) on my leg? It (they?) landed while Doug and I were canoeing around the local reservoir recently. They landed, flew away, returned, flew away, returned, on and on. If it's a them they spent a long, long time hooked up like that. And I mean hooked up in the sense that it's used most often these days.