I saw many net-winged beetles (Calopteron spp.) in a milkweed patch the other day.
Net-Winged Beetle, Calopteron sp.
I was enjoying the fragrance of the milkweed's flowers and watching the many, many insects feasting on the milkweed's nectar.
I noticed several individual net-winged beetles spending a great deal of time in this position (pictured above) as they visited milkweed flowers. I assumed they were imbibing milkweed nectar, since many other insects were doing the same thing. For example, the ant pictured below.
One interesting characteristic of the net-winged beetles is that they are chemically protected. The Calopteron have a noxious substance throughout their bodies which causes most predators to reject them. When the beetles are attacked, or in this case poked, they easily bleed... see the white droplets on the beetle's wing covers in the photo below. This exposes the predator to the beetle's odorous and distasteful substances.