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Photo#430648
Unidentified Fly - Cuterebra emasculator

Unidentified Fly - Cuterebra emasculator
Atlanta, Fulton County, Georgia, USA
July 22, 2010
Size: 1"
I don't post a lot of ID requests here because I can usually figure it out, but this one has me stumped. I found this fly crawling along the ground this morning, picked it up, and placed it in a terrarium. I've never seen one like it before. It is very soft, has a unique nose, and so far has failed to fly. Mostly it just crawls along a stick in the terrarium. Any help with ID would be greatly appreciated.

Images of this individual: tag all
Unidentified Fly - Cuterebra emasculator Unidentified Fly - Cuterebra emasculator

getting cooler by the minute -- thanks a lot, guys! great job.
Moved from Bot Flies.

Cuterebra emasculator, freshly emerged
Hi Tucker,
Great find! This is Cuterebra emasculator, also called the emasculating bot, although it does not really emasculate its host. It is a botfly parasite of small mammals. This is a very interesting species. In northern New England I only see this species in the Eastern chipmunk (Tamias striatus). But in the south this species seems to use primarily Sciurus carolinensis, the eastern grey squirrel (and other Sciurus such as the fox squirrel). We have Sciurus in the north so this is odd. Also in the north I always see the maggot in the groin area of the chipmunk, but reports from the south say these are often seen in the back, neck and sides of the body. I suspect (as Sabrosky 1986 hinted) that these may be two seperate species of bots, but that they look nearly identical? Sabrosky looked at hundreds of specimens and could not find a difference between species but he did not have access to modern dna techniques. I would love to be able to use your bot for dna studies. If you still have it I would love to get the specimen from you! I have specimens of the northern bot to compare to this one but I don't have southern specimens. My sister lives in GA so I have been wanting to get down there to look for this species. If anyone in the south sees this species, please collect it for me.
Your specimen likely emerged this morning. It looks very fresh. That is the reason it is not flying. The colors will get better by tomorrow. The brown rump will change to a more blueish black. It will become an extremely strong flyer soon. So be careful if you try to take more pics as they can fly fast! Bots can fly very quickly once they warm up. You should see some whiteish or yellowish hairs on the hind end of the rump, which helps ID the species. Will be a bit easier to see in 24 hours or so.
If you are hoping to keep the specimen, bots should be kept in a cage for a few days to let them burn off some energy. Bots do not feed as adults so need little care. But they only live for 10 days or so, depending on how active they are. They do not have fully formed mouth parts so they do not feed as adults. They store up fats from the host mammal and become flying fat reserves. You don't want to pin one like this on the first day or they will likely just rot in a year or so. Better to keep them in a cage for a few days to burn off fat and then pin it. If you leave it in a cage too many days it may get pretty beat up, so if it starts getting too active you may want to pin it.
Really a cool critter. Thanks for sharing the pics. We haven't seen many of this species on BugGuide, although they are a fairly common species east of the Mississippi River. They only fly as adults for a short time. Most specimens in collections are from July and into August. Sometimes the pupae will not overwinter and try to emerge in Sept/Oct although this is rare.
Thanks for the post. Feel free to contact me with any questions.

You can reach me direct at:

boettner@psis.umass.edu

George "Jeff" Boettner
Plant, Soil and Insect Sciences
115 Ag. Eng. Bld.
250 Natural Resources Road
UMASS-Amherst
Amherst, MA 01003

i alerted Jeff Boettner, he would know
always a pleasure seeing these gorgeous parasites

Moved
Moved from ID Request. Maybe an expert is more likely to see it here. Cuterebra emasculator seems close but I am NO expert and have no idea of the features required for an ID.

Try this
Oestridae (Bot Flies)

Also, please crop closer to "just the bug"

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