I found some interesting flies, Rhamhomyia longicauda, yesterday, and posted their photos on this blog. They have a fascinating life cycle–the males provide a nuptial gift of a prey item, and the females inflate their abdomens in order to make the males think that they are swollen with eggs. The male will select the female that he thinks is most likely to provide large numbers of offspring. I photographed the flies in sort of a resting state, not in the mating activity they are famous for.
I went back in the evening to attempt to see some lek display behavior or mating. I did not see either. However, I did find a male with a prey item.
Some dance fly species are reported to wrap the prey in silk. I did not witness that, and I only saw one male that had captured another insect. I did see several males, and they were all restless and apparently actively hunting.
I found a couple of females that appeared to be resting on leaves. Upon closer inspection, they had both inflated their abdomens.
I did not observe either female flying, although there are photos of inflated females flying on the internet.
All of the activity I observed happened during twilight–after the sun had set but there was still a little bit of light. The darkness made the photography difficult.
I will try again tonight and see if I see some more.