Mosquito with a puff-ball?
We were hiking in Citico Creek Wilderness of the Cherokee National Forest of east Tennessee, when we ran into groups of large mosquito-like insects flying around with large, white, air-filled balls, seemingly made of a material produced by the insect. They were flying around each other, as if in a mating dance! Occasionally one would land on a leaf and I was able to get this photo, what is it and what is the ball for? By the way, he is sitting on the leaf of an almost extinct American Chestnut sapling!
This has us mystified. It is a Dipteran but we do not know anything about the species nor the air balloon phenomenon. We have requested assistance from Eric Eaton. Here is Eric’s speedy response: “Hi, Daniel: That fly from Tennessee is a male dance fly (family Empididae). Males of some species present females with prey they have killed, as a pre-nuptial mating gift. This probably preoccupies her from eating him ! A few species “giftwrap” their prey in balloons like that shown in the photo. A few devious species will simply present an empty balloon. Cheapskates! This courtship behavior is not uncommon, but rarely seen, so kudos to the photographer for being so observant and curious. Find more images of this under Empididae at Bugguide.net . Eric “