Currently viewing the category: "Bot Flies"
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Subject: Weird, weird fly in Wisconsin.
Location: Wisconsin, USA
June 25, 2012 3:24 pm
Hi there,
Do you have any idea what the heck this is? I found it in my window — it’s about 1” long, very hefty. Apparently dipteran. This creature has a weird thing sticking out of the front of its head (mouthparts? emerging parasite?) and a couple of black upright ”fins” on its back just forward of the wing bases.
I’m an amateur entomologist and I’ve never seen the likes of this blighter before.
Thanks, and I’m interested in what you come up with!
Best wishes,
Signature: Rhian

Bot Fly

Dear Rhian,
This is some species of Rodent Bot Fly in the genus
Cuterebra.  Bot Flies are parasitic flies.  BugGuideprovides this graphic description of their life cycle:  “Females typically deposit eggs in the burrows and “runs” of rodent or rabbit hosts. A warm body passing by the eggs causes them to hatch almost instantly and the larvae glom onto the host. The larvae are subcutaneous (under the skin) parasites of the host. Their presence is easily detected as a tumor-like bulge, often in the throat or neck or flanks of the host. The larvae breathe by everting the anal spiracles out a hole (so they are oriented head-down inside the host). They feed on the flesh of the host, but only rarely does the host die as a result.”  We are copying Jeff Boettner to see if he is able to provide a species identification for us.

Bot Fly

Dear Daniel,
Thanks very much for the I.D. on that peculiar creature! The pictures in the link you sent look exactly like it, right down to the “fins” on the back (which I suppose are some kind of halteres?). That’s certainly a bizarre life cycle for a strange looking creature; for some reason, I thought bot flies were mostly tropical.
Thanks again, and keep up the good work with the site! 🙂
Best wishes,
Rhian

Jeff Boetner replies
Hi Daniel and Rhian,
Great shots. Yes, a Cuterebra botfly, this is one of the Cuterebra fontinella bots. You have two subspecies of this bot in WI, Cuterebra fontinella fontinella, which uses white footed mice as a host, and Cuterebra fontinella grisea, which uses deer mice as a host. The one you photographed is very freshly emerged, the wierd face is from a balloon like structure that inflates to help push the fly out of the pupal case, and then it gets reabsorbed back into the face. These guys don’t feed as adults so have no real mouth parts.
It is hard for me to do this one to species, but if you hung onto it, it might get better coloring after it has been alive for a few days. So if you can keep it alive, (they don’t feed so easy to keep), post another picture once the brown turns to white and black. I don’t see these this fresh, very often, unless I have reared one. Very fun to see.
I am doing dna work on bots, and I would be interested in the specimen. I don’t have dna from WI specimens, and still missing grisea if it turns out to be that one? Yours is female for sure from the spacing between the eyes.
Thanks for posting. And thanks for the forward Daniel. Love you site!
Sincerely,
Jeff Boettner
Plant, Soil and Insect Sciences
UMASS-Amherst
 

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Large fly(?) in Texas
Location: Dallas, TX
October 23, 2011 10:56 pm
Hello WTB
Please help me identify this LARGE fly(?) that my son found in our back yard.
– We live in North Dallas, TX
– It was found today, October 23
– It was found on a piece of playground equipment less than a foot from the ground
– It does not seem able to fly, but buzzes loudly when it attempts to
Thank you for all of your efforts. your site is my first stop when attempting to ID something new that we’ve found.
Signature: Brandon

Rabbit Bot Fly

Hi Brandon,
This is a Bot Fly in the genus
Cuterebra, and we are nearly certain it is the Rabbit Bot Fly, Cuterebra lepusculi, a species we just posted last week.  We are going to copy Jeff Boettner on our response so he can verify the identification since he has been providing correct species identifications for our Bot Fly submissions.  If you still have this specimen, Jeff may request it for study purposes.  Bot Flies in the genus Cuterebra are endoparasites of rodents and they have very interesting life cycles.  Your photographs are excellent.

Rabbit Bot Fly

Daniel –
Thank you for the quick response, and thank you for the compliment on the photos.  I’ve attached a much better photo here, now that I’ve had time to properly set up and shoot this one.
Jeff –
I just read your comments on WTB.  I appreciate all of the great info.  I will indeed post this on BugGuide.net.  I’m excited about your interest in this find.  This is a first for me, and I do a fair amount of amateur insect hunting and photography.
I do still have the live specimen, and would be happy to share it.  No eggs yet, but I will send those as well if they come.  How should I go about getting it to you in the best possible condition?
Feel free to look through the photos of my other finds on my website. The “nature” section can be found here:
http://www.themcmurrays.net/photos/nature/index.html
Kind regards,
-Brandon

Rabbit Bot Fly

Hi again Brandon,
Thanks for taking the time to take this stunning new photograph that is artful as well as accurately depicting the morphology of the Rabbit Bot Fly.

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GIANT fly
Location: Dallas, TX
October 17, 2011 9:53 pm
I’ve lived in Dallas, TX for 40 years and have never seen such a thing. Found today on our hydrangea plant. It has a fat head, thorax & abdomen, is mostly black with awesome horizontal red stripes across the top of its huge eyes, has white fuzz between the thorax & abdomen, and it’s wings fold in a crossed fassion, unlike most flies. Its legs are just like a common house fly (only larger) and it rubs them together and walks/behaves like a fly. When it flies it sounds loud like a bee. It’s about an inch long!
Signature: Grasshopper

Rodent Bot Fly

Dear Grasshopper,
This amazing fly is a Rodent Bot Fly in the genus
Cuterebra, but alas, we don’t recognize the species.  It doesn’t seem to match any of the species posted to Bugguidewhich describes the life cycle as:  “Females typically deposit eggs in the burrows and ‘runs’ of rodent or rabbit hosts. A warm body passing by the eggs causes them to hatch almost instantly and the larvae glom onto the host. The larvae are subcutaneous (under the skin) parasites of the host. Their presence is easily detected as a tumor-like bulge, often in the throat or neck or flanks of the host. The larvae breathe by everting the anal spiracles out a hole (so they are oriented head-down inside the host). They feed on the flesh of the host, but only rarely does the host die as a result.”

Rabbit Bot Fly

GIANT Fly – much better picture!
Location: Dallas, TX
October 17, 2011 10:30 pm
Please refer to my previous submission today.
thanks
Signature: Grasshopper

Rabbit Bot Fly

We will add this to the posting we already created for your amazing beautiful Rodent Bot Fly which we now believe to be a Rabbit Bot Fly, Cuterebra buccata, based on photos posted to BugGuide.

Wow, that is awesome!  Will definitely comment back!  Thanks Daniel.
Greg Hotchkiss, aka Grasshopper (my best friends actually have called me that since college)


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Grub Guy
Location: NE Pennsylvania
September 11, 2011 11:34 am
This is one of the strangest bugs I have ever seen. It appears to be some kind of grub as it has no feet. It moves slowly using a wave technique. It has two puffy orange objects by either its head or bottom.
We found it under our kitchen table. My mom thought it was a terd! It is almost black but a bit lighter nearer its orange orbs. We would love to know what this is
Signature: Thank You

Bot Fly Pupa

This is either a Pupa or a Pre-Pupal Larva of a Rodent Bot Fly in the genus Cuterebra which you can verify by comparing to this photo on BugGuide.  The mystery is how it go under your kitchen table.  Perhaps your household feline recently caught a rodent that was being parasitized by this endoparasitic Bot Fly.

Species Identification Courtesy of George Jeff Boettner and Eric Eaton
Hi, Daniel:
Can you copy and paste this to WTB?
Eric

Hi Eric,
George Jeff Boettner commented on your link.
George Jeff wrote: “Hi Eric, I can’t seem to post to the original site. If you can let them know this is a mouse bot, Cuterebra fontinella. It likely emerged out of a mouse walking across the table. So they should look around for signs of mice too! If put in soil and kept dry and outdoors for a year, they would likely get an adult bot next July or August.”

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huge black fly
Location: northwest
August 6, 2011 10:55 pm
I live in the country. Eagle creek Oregon. Found this in the laundry room. Its huge! All black. Little wings on top of its shoulders. Is it a horse fly? I’ve never seen a fly this huge before. Its crawling on a quarter!
Signature: Tina

Rodent Bot Fly

Hi Tina,
This is a Rodent Bot Fly, and we believe it is
Cuterebra tenebrosa which we identified on BugGuide.  These Bot Flies are skin parasites on rodents, and the host insect for Cuterebra tenebrosa is the wood rat.

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upstate ny, came out of dead rabbit
Location: Greene County, NY
July 24, 2011 4:44 pm
Have no clue.. it is alive and crawls around.. found it while cleaning a dead rabbit can you help
Signature: FoX83

Bot Fly Larva

Hi FoX83,
This is the larva of a Rodent Bot Fly in the genus
Cuterebra.  The larvae are endoparasites found on certain mammals.  The Bot Fly larva forms a warble, generally on the neck of the infested host, and though they look quite nasty, they are alleged to not harm the host.

What's That Bug? does not endorse extermination