Yesterday was cool and cloudy and not a good day for photographing butterflies. So I took some photos of flies. I found one that was new to me and got some photos. However, my work is not done–they have an amazing behavior that I would like to capture as well. Maybe I will get lucky and see it.
Here is the male Rhamhomyia longicauda. Kind of a long, ugly fly.
The head is mostly snout and eyes. Like lots of males, he brings home the bacon. That is, he captures small prey items, and flies around with them, competing with other males who might have larger prey items. The insect that he captures serves as a bribe so he can mate with the most fertile female he can find. That would be the the biggest, fattest, female.
This is the female. She is big and hairy–the hair might make her appear bigger than she already is. But she also inflates her abdomen to make herself seem even bigger and more fertile than she is. She mates with the male. She may be fertile and have a few eggs, but she makes the male think that she is much more fertile than she is.
I hope to be able to see the flies doing this display, and to photograph it. There is a photo on bugguide of this phenomenon that you can see now, however.