Currently viewing the category: "Bot Flies"
What's That Bug? does not endorse extermination

Subject:  Black bug
Geographic location of the bug:  Southwest Mississippi
Date: 10/03/2018
Time: 04:31 PM EDT
Your letter to the bugman:  What is this thing? Is it dangerous?
How you want your letter signed:  Judy

Bot Fly

Dear Judy,
This is a Bot Fly in the genus
Cuterebra, and it poses no threat to humans.  According to BugGuide:  “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 will attempt to contact Jeff Boettner to see if he can provide any species information.

Bot Fly

Thank you! I’ve heard of bot flies….mainly on Dr. Pol. Never thought I’d see one. I appreciate your help.
Judy
What's That Bug? does not endorse extermination

Subject:  Rodent Botfly?
Geographic location of the bug:  Portland, OREGON
Date: 08/06/2018
Time: 06:52 PM EDT
Your letter to the bugman:  I found this very large fly-like creature in my garden yesterday. After much research I came across photos on your site that led me to my tentative i.d. We have a growing rodent population in our yard since the last of the outdoor cats disappeared . I was stomping burrows closed when I found this thing and wonder if it might be a female that was laying eggs.I read that they lay eggs in/near the mouth of a burrow that hatch instantly to attach to a passing rodent. I wonder if these things (eggs) can attach to shoes or garden gloves and get tracked in the house. Creeeeeepy!!
How you want your letter signed:  Bjam, Portland, OR

Rodent Bot Fly

Dear Bjam,
You are correct that this is a Rodent Bot Fly and of all the species pictured on BugGuide, it appears most like
Cuterebra tenebrosa based on this BugGuide image.  According to a comment from Jeff Boettner on this BugGuide posting:  “The bot uses Neotoma (wood rats) as a host. They can get in the wrong hosts, if you had cuts on your hand or touched your eye. It would be pretty hard to get this bot in you, and would not be able to complete development in you at any rate. So easy to get removed if you found it trying to use you as a host.”  With many species of Flies, the sexes can be distinguished because the eyes of the male are much closer together than the eyes of the female, and we believe your individual is most likely a female.  According to BugGuide:  “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.”  If temperature was the only factor in the hatching of the eggs, heatwaves would cause eggs to hatch with no nearby host, so in our opinion, the hatching of the eggs might be more complicated.  If eggs were tracked into the house, and there was no host present, the larvae would die.  We will contact Jeff Boettner to see if he can verify the identity of your Rodent Bot Fly and to see if he can provide any additional information.

Rodent Bot Fly

Thanks for the quick reply.
I used to work for a veterinarian and we occasionally saw cuterebra larvae in dogs. Impressive.  Have also seen deer mice that carried 3 or 4 or more larvae. They were almost more maggot than mouse.
We don’t have woodrats here so I suspect deer mice, voles, possibly chipmunks and rats are main hosts.
Thanks again for response.  Love this site.  It’s a great resource!

Jeff Boettner responds with correction.
Daniel–Not a bother at all. Love these. But I am not sure what you have yet!  For sure NOT C. tenebrosa (which lacks the spotting of yours on the abdomen) but it is female.
Looks like a Peromyscus bot of some sort. It looks from the picture,  like the person might have collected it? We created a team of people to do dna sequencing to work out some of these tricky ones, if the person is willing to part with it? I am ccing Socrates on this (he is starting up a PhD project this fall on bot evolution and can really use samples of even common bots that show up). This would be a really nice one to see in hand.
Nice pics!  I should be able to figure out a name but I want to think about this one more. These mostly black females are tricky. But I am quite sure this is not C. tenebrosa
Socrates: See pics at this site:  2018/08/07/rodent-bot-fly-12/
Will get back to you soon.
Jeff Boettner

Additional information from Jeff Boettner
I think your bot is Cuterebra approximata female. Will see if he thinks so too. Generally these females are all black but the range fits and the males have spotting on the abdomen similar to yours. These mostly black females are very tricky. But this one uses Peromyscus maniculatus as a host, and is found in OR.  Would be a really nice one to preserve.
Jeff

Thanks for this info. Unfortunately, I released it after a couple of days. I have the glass it was in with a good smear of fly poop if that would be of any use. Also more photos.
Bjam

What's That Bug? does not endorse extermination

Subject:  Fly?
Geographic location of the bug:  Greely Colorado
Date: 08/04/2018
Time: 02:56 PM EDT
Your letter to the bugman:  This little guy was found in a back yard. The fingers are those of a toddler who would like to know what this is. I can’t find it by googling.  Thank you for any help!
How you want your letter signed:  Mallory

Rabbit Bot Fly

Dear Mallory,
Most people who encounter a Bot Fly in the genus
Cuterebra for the first time confuse it for a Bee.  According to BugGuide:  “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.”  BugGuide also notes:  “Habitat is less important to these flies than the host mammals. Habitat-specific rodents or rabbits means habitat-specific species of bots.”  We believe your individual is a Rabbit Bot Fly, Cuterebra buccata, which is pictured on BugGuide.  We have written to Bot Fly expert Jeff Boettner to confirm its identity.  Do you have any additional camera angles?

Rabbit Bot Fly

Jeff Boettner responds.
 Both C. leupusculi and C. buccata are possible in Greely, CO. Both these species look a lot alike from the side, but the coloration of the back hints more of C. leupusculi. I think this is a male but also hard to tell from this angle and there are only 15 C. leupusculi males in collections, females are more often seen. Males may lek, ie if you went back to this same spot at the same time of day, you might see males fighting over that rock or the nearby area? Do you have any other pics from any other angles? Even slightly different angles.
C. buccata uses S. floridanus,  whereas C. lepusculi uses S. audubonii but both rabbits overlap in that location. So a bit tough to call. But for sure a rabbit bot, and likely one of these two.
Jeff

What's That Bug? does not endorse extermination

Subject:  Should I be worried?
Geographic location of the bug:  Eugene, OR
Date: 12/01/2017
Time: 04:02 AM EDT
I found three of these really gross larva inside my house this week, November 2017. Based on internet searches, I think this may be a bot fly larva. We have cats which like to bring us “mice” presents which are not always dead. These larva were found in the room where I had caught the mouse the day before. If you kill the mouse would the larva try to leave the body or should I be looking closely on the cats assuming this a bot fly larva?
How you want your letter signed:  Grossed-Out Becky

Immature Bot Fly

Dear Grossed-Out Becky,
We concur that this is an immature Bot Fly.  Rodents are typical hosts, but we believe we have read that rarely a domesticated pet may also act as a host

Thank you for your quick response.  I’m checking my cats just in case.

What's That Bug? does not endorse extermination

Subject:  Hornet eating strange bug
Geographic location of the bug:  Portland, Oregon
Date: 09/11/2017
Time: 05:27 PM EDT
I was curious what bug is being eaten, I’ve never seen one before.
How you want your letter signed:  Heather lux

Yellow Jacket preys upon Bot Fly

Dear Heather,
The prey in your image is a Rodent Bot Fly, and the predator appears to be a Yellowjacket, a close relative of Hornets.  Adult Yellowjackets prey upon various insects, especially caterpillars, to feed to larvae that are developing in the paper nest they build.

What's That Bug? does not endorse extermination

Subject: Unidentifiable bee?
Location: Southeast Michigan
April 28, 2017 10:30 am
Dear bugman,
I found this bug in my bedroom this morning. Cool looking! What is it?!
Signature: Julie Jones

Rodent Bot Fly

Dear Julie,
Though it is frequently mistaken for a Bee, this is actually a Rodent Bot Fly in the genus
Cuterebra.

What's That Bug? does not endorse extermination