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Heymatt-- Do flies go to the bathroom, deposit feces?

-- Devon Davis, 782 CBSSS/PK

Hi, Matt:

The flies in my home seem slower than usual, and I am serious. They hop around on the floor as they seem to be slowing down nearing death or something. They are easy to kill since they are so slow. I find multiple dead flies on my windowsills. We do not use pesticides. We have a newer home that I keep clean. Is there a natural occurrence for flies when they are trapped in a home to get slow then die, or are the flies trying to tell me something about our home?

-- Brandi Lohr, East Bay Area

Devon's address is secret code for Robins Air Force Base in Georgia, according to our cryptology elves. How did the flies get past Homeland Security? Man, this country's like a leaky sieve. Anyway, flies gotta eat, flies gotta poop, and the whole business is pretty disgusting. Houseflies follow their "noses" to a likely food source (almost anything). If it's liquid, they soak it up like a sponge. If it's a solid, they throw up something we'll call SFS (special fly spit) that liquefies the food, and then they suck it up. Flies' mouths are soft and spongy; they can't chew. In pretty short order, the food is metabolized, and they poop out the rest in what we usually call "fly specks." Fly poop is tiny black or brown dots. You might also find amber-colored spots, but that's excess SFS left over from the meal. Now go back to work, Devon, and stop goofing off on the taxpayer dollar.

Brandi's lethargic bugs are another thing altogether. I'm hoping we hear from others who seem to be running a fly hospice to see if Brandi has company. Cold weather slows flies to a crawl, of course. But that would have to be continuously under 50 degrees or so. Our Dr. Bug says it's unlikely something like radon in your home is killing them. Flies only live 15 to 20 days or so. Not enough time for long-acting agents to kill them. Given their feeding habits, they have good gut microbes to protect them. And flies reproduce so quickly, they often develop resistance to common chemicals.

Flies enter a house when they "smell" food, not just randomly because they like your drapes or something. When they're not eating or looking for manure to reproduce in, they tend to hang out as close to the ceiling as they can get. Unless you have a rug made of pork chops, they'll stay off the floor. If this is an ongoing problem, Dr. Bug is baffled. If it's a one-time thing, it seems you were attacked by an odd swarm of geriatric flies who moved in but couldn't figure how to move out. (A few met their fate bashing themselves against your window glass.) Anyone else have a big slow-fly problem?

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cmorianti Dec. 17, 2014 @ 8:21 p.m.

I know it's been 7 years since this was originally posted, but hopefully someone is still monitoring it. I also have a slow fly problem. I live in Michigan and they come into my bedroom on the third level of my condo, probably through a window or my patio door. The kitchen is two levels down. The furnace and washer and dryer are also on this level. The flies usually die within 20 minutes of me noticing them. The reason I'm so interested is because I have had laryngitis for 10 months and I'm wondering if my condo is making me sick.


GDARWIN July 3, 2018 @ 9:33 p.m.

have the same problem with flies in my house. i don't use any pesticides but i find dead flies on counter tops, on tables and on the windowsills. i thought maybe co was killing them and that there might be a source of co in the house that could be affecting me and my dogs. what do you think?


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