What's That Bug? does not endorse extermination

Subject: bug mystery in quebec
Location: my yard, near montreal and quebec city, quebec, canada
July 19, 2015 3:45 pm
hi there bugman. found a bug, couldn’t identify it, we’re curious if you can help us. it was pooping white/transparent goop, head upside down in the grasses of my yard. location: southern quebec, canada.
Signature: s+r

Rodent Bot Fly Ovipositing

Bot Fly Ovipositing

Dear s+r,
You images are a thrilling addition to our archives.  This is a female Bot Fly in the genus
Cuterebra, and she appears to be in the process of laying eggs, the “white/transparent goop” that you observed.  Rodent Bot Flies are parasites of rabbits, mice, squirrels and other rodents.  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.”

Rodent Bot Fly Ovipositing

Bot Fly Ovipositing

Jeff Boetner, Bot Fly expert, provides some information.
Hi Daniel,
Nice pics. This is a relative of your mystery FL bot from a week or so ago. But this one we can ID as Cuterebra fontinella fontinella. This is a nice shot of a freshly emerged female. The fontinella bots are known for the white rumps on the last segment of the rear end. This is a huge female, they can lay over 1,000 eggs in their short lives. Most eggs are laid in mouse runways or near burrows. The fluid you saw was likely because the female just emerged from her pupae (in the soil). Bots have no mouth parts or digestive tract so no need to poop. They have to store up all their energy they need as adults, by feeding as a maggot in the mouse host, and this one did a good job of that, judging by her big body size. This one is a specialist on white-footed mice, Peromyscus leucopus. This species is our most common bot, yet not found as often as you would think. I have trapped over 200 mice per hectare*. in our plots in MA, and sometimes 80% will have 1-2 bots, so you would think there would be huge numbers out there. And yet many entomologists I have met, have never seen one in the wild. So consider yourself lucky…(or unlucky if you are a white-footed mouse).
Jeff

*a hectare is approximately 2 1/2 acres.

Thanks a lot for the quick answer, dude/dudette(s)! We weren’t expecting close to this quick of a response. I’ll be sure to bug you again for some more IDs (hohoho).
-Simon

What's That Bug? does not endorse extermination
Location: Montreal, Quebec, Canada

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