What's That Bug? does not endorse extermination

Squirrel insect
These grubs or insects showed up in my cabin along with a dead squirrel the cat brought in. Could be that its a coincidence or perhaps the cat brought them as an additional gift. The insects were not on the squirrel. Can you help me identify these so I can decide weather they a friend or foe.
Rick in Western Colorado

Hi Rick
Here is one sure to gross out our readership. These are Rodent Bot Fly Maggots, Cuterebra species. The Rodent Bot Fly is a mammalian endoparasite. According to a website we located: “The female flies will lay their eggs along rabbit trails and near rodent burrows. The first stage larvae will hatch and quickly attach to hair when a host brushes against the egg. The larvae then burrow into the skin and leave a breathing hole. ” Also on the website is the information: “Cuterebra is a normal bot fly of rodents and rabbits, but can also infect cats, dogs, and man. The adult fly looks like a bumblebee and is rarely seen. It may appear a shiny blue or black color. The third stage larva is dark brown to black with stout black spines. ” Your close-up photo shows the mouth hooks of the maggot, substantiated by this image on BugGuide. Bot Flies are also known as Warble Flies due to the lumps visible on the skin of the hapless host. There is also a Human Bot Fly, Dermatobia hominis, that is found in Central America.

Wolves on Rabbits
(08/15/2007)
Daniel…
After just reading your description of the bot fly larvae, I’m wondering…at certain times of the year (usually late summer, early fall) when my father would go rabbit hunting, (we actually depended on them for food in the ’50’s), they would sometimes get rabbits with what they then called ‘wolves’ in their necks and we were not allowed to use them for a food source. Could it be that I’ve learned after all these years that these were actually bot fly larvae? I large lump would most times be visible. Does this actually damage the meat for human consumption? Thanks for taking the time to read my query and if you have time to answer, that would be great, but if you don’t, I understand…. Sincerely,
Pat, Hawk Point

Hi Pat,
It sounds like your rabbits with wolves were parasitized by a Bot Fly. The meat near the wolf or warble might be unsavory, but cooking the meat would definitely kill the parasite.

Joanne Gets Sick!!!(08/15/2007) The Rodent Bot Fly
Will you pay for cleaning my nice leather recliner cuz I just barfed on it.
Joanne

Close Encounter with a Human Bot Fly!!!
(08/15/2007) Human Bot Fly experience
Hello fellow bug-nuts,
Your recent posting of the rodent bot fly larvae brought back some interesting memories. I brought an unexpected souvenir home from a trip to Costa Rica in ’00. You guessed it. Luckily, I’d read about these critters. Made me the hit of my local doctor’s office. I actually printed a page from a Canadian website and brought it along in to prove I knew what I was talking about. It is a very weird sensation to feel these beasts move when they’re in your flesh (mine was in the flab of my upper left arm). You can actually feel the bristles they anchor themselves with as they twist about. The research I did told me the adult female bots actually wrestle a mosquito down and lay an egg on the mosquito’s abdomen. Then the mosquito bites a host, the egg on her belly hatches (very quickly, apparently), and the newborn enters the mosquito’s bite site. My research also gave me the bot’s larval timeline, so I knew how long I had, and how insistent to be at the doctor’s office. Love your site! I check it every day.
Don J. Dinndorf
St. Augusta, MN

Bot Fly Larvae are Edible
edibility update on bot fly
Hi Daniel,
Just to keep the gross-out fest going, and to answer Pat’s question: I’m pretty sure that NO, the presence of bot fly larvae would not render the host animal inedible. There’s a good deal of documentation [as recent as 1918] of Inuit hunters taking down caribou that were infested with large fly larvae, and then making a point of cooking and eating the larvae first. Not sure if I could do it, especially considering the textural issue of those rough, stubble-like projections all over the larvae’s sides, but the point is that if some people enjoyed eating the actual flesh-consuming maggots, then eating the rest of the animal would not be a big deal. Reluctance to do so is pure ‘fussiness’ on our part. Best,
Dave
www.slshrimp.com

What's That Bug? does not endorse extermination
Location: Colorado

7 Responses to Rodent Bot Fly Maggot (and it's edible)

  1. Arlyne Bordelon says:

    I have recently come to know a little bit about the Bot fly larva. We have had more rats around our house than usual and I suspect they are the hosts. We also have three dogs and am worried about their worries. What can I do to prevent them from becoming a host. I happened to find these crawling on the carport (not on the rats). How long do they live without a host and is there something I can put out to kill or run the off? Any help will be greatly appreciated…Thanks

    • bugman says:

      If you found a Bot Fly Larva that was not attached to the host, we suspect it was searching for a place to pupate. We do not provide extermination advice.

  2. SarahD says:

    My bf lives in North Plains, OR which is in the Great NW. We found a chipmunk that the cat killed on our patio this am. There were at least 4 warbles on the chipmunk w late stage pupae in and leaving the body. They are large!! We had no idea that there are rodent bot flies in NW Oregon. Fascinating but gross, not to mention a little worrisome on behalf of our pets. It is a country setting and our critters are always romping and investigating the woodsy areas around the house. Is the rodent botfly common in our area? Why have we never seen rodents w warbles before now? Our cats bring home rodent corpses often. Any factual info or references is appreciated! !

    • bugman says:

      BugGuide lists Rodent Bot Flies in the Pacific Northwest, but we don’t know how common they are. We imagine like with most insects, there is no consistency of populations within or throughout the range. Checking with you local natural history museum might be the easiest way to determine the information you desire.

  3. Charlene Ridgway says:

    Twice in the last week my dog caught a mouse that wasn’t quite normal. After researching on your site, I’ve come to the conclusion that both times the mice had rodent bot flies. The mouse today was still alive, but the larvae was just emerging. My question is: is it common to have rodent bot flies on the Washington coast? Can my dog get them?

    • bugman says:

      Rodent Bot Flies, according to BugGuide, are found throughout North America. It is rare but not impossible for a domestic cat or dog to be parasitized by a Bot Fly.

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