Look What I Caught!
August 3rd, 2007 by Kelley
A botfly! Let me tell you, I watched this fly buzz around for about 3 minutes before I realized what it was. And of course I know I looked like a crazy nerd as I chased after it, such is the life of an entomologist 
These flies belong to the family Oestridae, genus Cuterebra. They are parasitic flies and the females deposit eggs onto the skin of vertebrate hosts. Body heat from the host triggers the larvae to hatch and burrow underneath the skin. The larvae encyst below the skin and cause a lump that is known as a warble. The larvae feed on host body fluids, not necessarily blood. Just before pupation the larvae bore out of the host and finish development in the soil. Adults do not feed, and in fact, have vestigial mouth parts.
We only have one genus (and some 26 species) in the US. The species we have only parasitise rodents and horses. Human botflies have a distribution limited to the tropics.
One of the most disgusting things I’ve seen is a bot fly on the belly of a rat in Ecuador. It wasn’t so much that it looked disgusting as much as it was the smell which threatened to bring back your last meal… I was really surprised because I’d known of bot flies for some time, but never imagined them to be so large. This thing was more like a grub than a maggot. I suppose like everything else there’s variability in size among species?
Hi Kelley,
Have you told Jeff Boettner about your bot find.
He’s a bit of a bot expert and can ID it for you, he’ll also be psyched to know your collecting locality.
Rodger