Subject: Fly identification
Location: Masai Mara, Kenya
December 31, 2013 2:45 pm
We were hoping that somebody in your institution could help us identify this insect we saw at a lodge we were staying at in the Masai Mara. It was a couple of inches long and was the biggest fly we have ever seen!
Please would it be possible for someone to give us an idea of what sort of fly it was? We would really appreciate your help.
This appears to be a Robber Fly in the family Asilidae, a group of predators that can take large insect prey while on the wing. We have several other photos of large Robber Flies from Africa in our achives, including this Proagonistes species from South Africa and this Carpenter Bee Robber Fly, also from South Africa. The one other possibility that we are considering is that perhaps this is a Bot Fly in the family Oestridae. The organs at the base of the wings, which we believe are called calypters, are distinctive in Bot Flies and this individual has very developed ones, however the furry legs remind us more of the legs of a Robber Fly. As an aside, while researching this posting, we learned that the largest fly in Africa is the Rhinoceros Bot Fly, Gyrostigma rhinocerontis, and you can view a photo of it on Natural History Museum.