There was a previously closed thread about this here https://forum.inaturalist.org/t/chipmunk-bot-flies-wa/25627, I have a similar situation where several chipmunks have botfly on them. Some are so large I’m worried if they’ll be okay. My question to the group & original poster @boattailedgrackle is did the wounds heal alright? They are really horrific.
Also, is common during summer in pnw? I don’t recall seeing this before.
Follow up questions:
I observed a very large brown rat chasing/lunging at chipmunks and I think he it may be hunting them. They are several babies and the rat is about 4x as big. It’s strange because the rat is out in the daytime and very aggressive. I’m going to try and trap him at night I think, not really sure how to get rid of a rat without harming other small rodents.
Can the presence of rats be the cause of the botflies showing up?
you may want to try calling someone at WA Fish and Wildlife.
That was a great idea, thank you. They said these should resolve itself after the botfly leaves and luckily none of the chips are immobilized that I can see. They suggest wait it out and only if one seems in crisis from it to try and remove the larvae or have a wildlife vet do it. Seems reasonable so that’s the plan. Wow though, total nightmare fuel. 
Just now seeing this! sorry for the late reply, yes! the once the botflys wriggled out and left their hosts, the holes closed within a few days or so, I was honestly quite surprised by how fast some of them healed up, they will have a bald patch of fur about a month after the botfly hole though.
They are more of an end of summer thing, they like warm sunny areas and tend to bother peoples livestock and horses as they livestock tend to hang around warm sunny dry fields and pastures.
With more rodent hosts in the area (the rat presence) it could possibly increase possible botfly numbers, they like to lay their eggs outside of rodent dens and holes so the larvae can attach themselves on the hosts body as they enter/exit. That certainly sounds like a scary rat you described.
This year the botflies have not been as bad in my area, perhaps they have their ‘emergences’ like cicadas where some years there are tons of them, and other years not so much
Thanks so much for the reply and yes most have left now and it’s shocking how quickly they are healing! One poor guy had attached to his cheek and you can barely tell. I suppose botfly looks the worst at the point just before it leaves. I think you must be right, the official I spoke with knew what I was talking about but said she hadn’t see any this year… yet. Could be just a bad year in my neighborhood. Interestingly I haven’t noticed any of the actual flies now that I’m on the lookout.
I’m very relieved to learn it’s just something temporary and they bounce right back 
I honestly thought botflies were native to South America (no idea why), until my uncle recently showed me a picture of one he managed to remove from the head of an abandoned kitten. I have never been so grossed out, more so because it wasn’t just a YouTube video from somewhere far away, it was something that happened just a few miles from me. Knowing botflies are not that uncommon up here in The Catskill mountains, has me creeped out and slightly terrified. The ticks are bad enough! Anyway, the botfly had grown so large, the poor kitten’s head had doubled in size. The maggot (?) that was removed was the size of a thumb. The hole it left on the kittens head would leave one to believe that the damage it had caused, could easily have killed the baby cat. My uncle thought he’d killed the kitten when he removed the maggot, but it turned out the poor thing just fainted. Whether from shock or pain, I’m not sure. But my uncle was able to put antibiotic ointment on the wound before the kitten woke up. As it turned out, a stray cat had given birth to three kittens beneath my uncles house. The mother cat brought a dead rabbit back to their “nest”, which is probably how the botfly ended up on the kitten. From what I’ve heard, they tend to lay eggs in open wounds or flesh cavities. Now I’m scared to go outside with so much as a scratch. I liked it better before I knew botflies were common here, on wildlife as well as cows and horses. It’s times like this I truly understand the statement “ignorance is bliss”. I’ll actually text my uncle now to see if he can send me the pictures.
would putting a bandaid (or similar wound covering) over your scratches help you worry less about it?
The botflies that normally infest humans are found in the neotropics, but there are many botfly species in north america, which typically parasitize either large herbivores like deer and cattle or rodents and other small animals. Its exceptionally rare for botflies found in the US to parasitize humans.
They don’t generally lay eggs on wounds or flesh cavities- the larvae find a way to enter intact skin, or in deer botflies and relatives they enter the mouth or nose and develop in the digestive tract (often when the host attempts to lick the eggs off of its fur). In rodent botflies, the flies don’t lay eggs directly on the host, but lay eggs on the ground or vegetation for the young larvae to find hosts themselves, and human botflies lay an egg on another biting insect like a mosquito so the egg hatches when the mosquito bites a host.
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