# Where are all these f'ing flies coming from? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [August 28, 2025, 10:31pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565 "2025-08-28T22:31:27Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [August 28, 2025, 10:31pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/1 "2025-08-28T22:31:27Z")
Yesterday we had an explosion of flies emerge, probably from the downstairs bathroom, which at one point had about 20 flies. They spread through the house, most of them rather slow and stupid and easy to kill. But we killed at least 50, perhaps more, using swatters and sticky traps. We seem to have gotten the upper hand, but there are still a few popping up. This has happened a few times before, but on a much smaller scale. It usually ends after a few days. It may happen that way this time, too, Og willing. We’ve called a local exterminator, but haven’t heard back from him yet. Any idea where they can all be coming from, what we can do to prevent these explosions, and how best to kill them? ---
**Author:** ![Procrustus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/procrustus/32/2994_2.png) [@Procrustus](https://boards.straightdope.com/u/Procrustus)\ **Post date:** [August 28, 2025, 10:36pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/2 "2025-08-28T22:36:37Z")
Until we blocked rat access to our walls and ceiling areas, we had fly explosions once or two per year. Hundreds of them at a time. (they were slow, and we just vacuumed them up) (when we opened up our walls, we found many mummified rats) So, my guess is you had a dead animal somewhere. ---
**Author:** ![Dewey\_Finn](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dewey_finn/32/4222_2.png) [@Dewey\_Finn](https://boards.straightdope.com/u/Dewey_Finn)\ **Post date:** [August 28, 2025, 10:46pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/3 "2025-08-28T22:46:20Z")
If you have an electrical outlet nearby, I recommend these [Zevo insect traps](https://zevoinsect.com/flying-insect-trap-starter-kit/), which work great for flying insects. They have a blue light to attract insects and a sticky surface to trap them. ---
**Author:** ![Spice\_Weasel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spice_weasel/32/5435_2.png) [@Spice\_Weasel](https://boards.straightdope.com/u/Spice_Weasel)\ **Post date:** [August 28, 2025, 11:17pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/4 "2025-08-28T23:17:18Z")
> [@commasense](#): > > Any idea where they can all be coming from, what we can do to prevent these explosions, and how best to kill them? This is what worked for us this summer: Stopped 'em cold. > **[Amazon.com : Ortho Home Defense Insect Killer for Indoor and Perimeter2 with...](https://www.amazon.com/Ortho-0221500-Defense-Insect-Perimeter/dp/B01N0TGJHB)** > > Ortho Home Defense Insect Killer for Indoor & Perimeter2 kills common household bugs such as ants, beetles, centipedes, cockroaches, crickets, fleas, flies, millipedes, mosquitoes, moths, spiders, stink bugs, ticks, termites, periodical cicadas and... Good luck. Flies are hideous. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [August 28, 2025, 11:20pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/5 "2025-08-28T23:20:05Z")
It would help to have an idea what _type_ of flies. There are over 100,000 species with very diverse habits, habitats, and food sources. This is like asking where rhese mammals are coming from and you don’t say if it is squirrels or wolves. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [August 28, 2025, 11:43pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/6 "2025-08-28T23:43:46Z")
> [@commasense](#): > > Yesterday we had an explosion of flies emerge, probably from the downstairs bathroom, which at one point had about 20 flies. They spread through the house, most of them rather slow and stupid and easy to kill. But we killed at least 50, perhaps more, using swatters and sticky traps. Is [your house](https://www.youtube.com/watch?v=PQseahtPVAA) the site of a violent multiple murder, build on a Native American burial ground, or at a locus of alignment of ley lines? Stranger ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [August 29, 2025, 3:52am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/7 "2025-08-29T03:52:05Z")
I’ve noticed anywhere we’ve deposited corn husks or potato peels, or a banana peel. And kind of fruit or veg leaving it will swarm with flies in a couple of hours. This would be outdoors. I often leave the scraps for wildlife, trying to keep them out of the burn barrel. I could see it being a problem if it were near an open door. Block their way, as best you can. Remove dead plant material from near entrances. (And any corpses 😊 ), spray and swat. But yeah. Home pest control should do it. I like the Zevo brand, myself. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [August 29, 2025, 4:05am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/8 "2025-08-29T04:05:26Z")
> Is [your house](https://www.youtube.com/watch?v=PQseahtPVAA) the site of a violent multiple murder, build on a Native American burial ground, or at a locus of alignment of ley lines? Only two of those three. Why? ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [August 29, 2025, 4:10am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/9 "2025-08-29T04:10:23Z")
Oh, flies love love apple cider vinegar. Keep that from trash cans or the sink. If you spill or splash wipe it up. I like to spray some cleaner that smells loud to cover any lingering odor. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [August 29, 2025, 4:28am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/10 "2025-08-29T04:28:13Z")
> [@commasense](#): > > Yesterday we had an explosion of flies emerge, probably from the downstairs bathroom, which at one point had about 20 flies. What kind of flies? Are they house flies, drain flies or another kind of fly? If they are drain flies, they could be coming from your drains (surprisingly). There are compounds you can pour down the drain that will kill them off, but it can take a couple weeks to truly see effects. ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [August 29, 2025, 5:00am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/11 "2025-08-29T05:00:06Z")
> [@Darren\_Garrison](#): > > It would help to have an idea what _type_ of flies. There are over 100,000 species with very diverse habits, habitats, and food sources. This is like asking where rhese mammals are coming from and you don’t say if it is squirrels or wolves. > [@Wesley\_Clark](#): > > What kind of flies? Are they house flies, drain flies or another kind of fly? How do I tell what kind of flies I have? They look to me like ordinary house flies. They’re big and black. The ones that recently emerged were mostly slow and easy to kill, not quick and cunning, like some flies. We are sometime bothered by much smaller midge- or gnat-like critters, less than a millimeter long, but these are much bigger, ~5-8 mm from head to tail. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [August 29, 2025, 5:12am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/12 "2025-08-29T05:12:43Z")
> [@commasense](#): > > Only two of those three. Why? Well, you either need a priest or a group of paranormal investigators with deep knowledge of the occult and an a crazy-eyed codger who mutters under his breath and is must barely hanging onto his last few points of SAN. Stranger ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [August 29, 2025, 6:25am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/13 "2025-08-29T06:25:54Z")
> [@commasense](#): > > How do I tell what kind of flies I have? Photograph them. Do a Google Lens search. Or look on Bug Guide > **[Order Diptera - Flies](https://bugguide.net/node/view/55)** > > An online resource devoted to North American insects, spiders and their kin, offering identification, images, and information. ---
**Author:** ![Beckdawrek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beckdawrek/32/3647_2.png) [@Beckdawrek](https://boards.straightdope.com/u/Beckdawrek)\ **Post date:** [August 29, 2025, 7:29am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/14 "2025-08-29T07:29:04Z")
Why does it matter what brand of fly they are? Swatter kills all of them. If it’s a horse fly you might have to whack it a couple of times. ---
**Author:** ![kambuckta](https://avatars.discourse-cdn.com/v4/letter/k/53a042/32.png) [@kambuckta](https://boards.straightdope.com/u/kambuckta)\ **Post date:** [August 29, 2025, 7:55am UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/15 "2025-08-29T07:55:22Z")
About a year ago I had a sudden influx of flies, and like the OP, they were slow and sluggish. I had no idea where they came from (common house flies FWIW) but a squirt with flyspray despatched them in no short order. I wonder if they’ll come back again this year, same fly time, same fly channel? 😛 ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [August 29, 2025, 12:28pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/16 "2025-08-29T12:28:04Z")
> [@Beckdawrek](#): > > Why does it matter what brand of fly they are? Because different types of flies live and breed in different environments and have different food sources both as adults and as larva. So it matters because it _helps answer his question_. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [August 29, 2025, 12:35pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/17 "2025-08-29T12:35:52Z")
You may be experiencing Cluster flies, but they’re more common IMO during the colder months. > **[Cluster fly](https://en.wikipedia.org/wiki/Cluster_fly)** > > Cluster flies (a.k.a. grass flies or attic flies) are flies of the genus Pollenia in the family Polleniidae. Unlike the more familiar blow flies, such as the bluebottle genus Phormia they do not lay eggs in human food. They parasitise earthworms; the females lay their eggs near earthworm burrows, and the larvae then feed on the worms. But the biology of this group is relatively poorly known and a few have been recorded from other hosts including caterpillars and bees. > Cluster flies seek refug... ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [August 29, 2025, 12:48pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/18 "2025-08-29T12:48:30Z")
> [@Spice\_Weasel](#): > > Good luck. Flies are hideous. There was a butcher shop just off of the main street in my hometown that had an electrified grid on the windows that were located on either side of the garbage area. When I was in grade school and it was warm/hot, I’d stop every once in a while to see them fly into the grids and get electrocuted. BZZZT!, and their lifeless bodies would tumble through the air and bounce on the ground. My brother, who happened to be with me one day when I decided to stop there, told me I was sick. LOL ---
**Author:** ![DCnDC](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dcndc/32/2842_2.png) [@DCnDC](https://boards.straightdope.com/u/DCnDC)\ **Post date:** [August 29, 2025, 12:50pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/19 "2025-08-29T12:50:41Z")
If they have black and white stripes, they’re flesh flies, which have a fairly wide size range and can get pretty big, almost an inch at the extremes. ---
**Author:** ![chela](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chela/32/21582_2.png) [@chela](https://boards.straightdope.com/u/chela)\ **Post date:** [August 29, 2025, 1:31pm UTC](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565/20 "2025-08-29T13:31:47Z")
How quick on the draw are you? You must try a salt gun it’s a plastic, pump-action shotgun that blasts pests with table salt [Next page](https://boards.straightdope.com/t/where-are-all-these-fing-flies-coming-from/1022565.md?page=2)