No quick way. We had this happen at two houses.

#1) We had crank out windows and I'd leave the latch swung out. They were getting in the latch for the window. If I swung the latch shut..gone!

#2) Up by the beam on the ceiling, you couldn't see it from the ground, there was an 8" x 4" hole near the ceiling beam where the beams came together. Closed it up. Gone!

We had wasps coming in via a ceiling light fixture!

I suspect they're in, not getting in, and reproducing in place. Try to get all of them however (whether with traps or fumigating or both) and that hopefully will resolve the problem.

I once lived in a rental that had cedar paneling, including the ceiling, which looks like you might have, as well? The outside was cedar shingles with a cedar shake roof. We were inundated with flies that would appear from nowhere. It appeared they would sun themselves on the outside of the house, and perhaps lay their eggs under the shakes. When the sun warmed everything up, they hatched and worked their way into the house. It was always much worse on sunny days. Sometimes even sunny winter days. If I remember correctly there was no insulation in the ceiling, so nothing to act as a barrier but the boards.

Sorry I have no solution; offering this as a potential cause. I feel your pain.

I can’t edit my post. They always seemed dopey when they first appeared, like they came out of hibernation, which kind of supported our theory they were hatching under the roof. Right now our area is being inundated with stink bugs. Not too many get in the house, but any sinny atea outside has swarms of them . I have a stand alone garage, so get covered with them trying to get to the car. I read about these traps and am going to try them near my garage. I’m desperate! They might be another way to catch flies.

Zevo:

https://www.homedepot.com/p/ZEVO-Indoor-Flying-Insect-Trap-for-Fruit-flies-Gnats-and-House-Flies-1-Plug-In-Base-1-Refill-Cartridge-83535451/317014720

one year i had them coming in through my bathroom skylight. had a guy come and seal around it both inside and on the roof. never had the problem again. **knock on wood**

We call, what I believe you’re experiencing, Blowflies. something dead and rotting is the host. Most likely in your attic, attic crawl space, etc. They tend to be on the large size, at least the first surge of them, and are very bumbling and slow when I first start seeing them inside our home, Which happens, unfortunately, at least once a year here, usually during the Summers. In fact, I’m just now getting rid of the last of them. An average number of hatchlings at one episode is at least 40! Usually more! I wish that I has a solution other than fly swatters. Ours is a one story adobe hacienda with all wood and beamed ceilings. And no crawl space for humans but, sadly, enough space for mice to occasionally get in and die. Ugh!

Socks, you might have cluster flies

https://en.wikipedia.org/wiki/Cluster_fly

Snap a macro photo? Use a dental mirror, get the fly in focus in the mirror, then snap a photo of the fly’s refection.

Wash dental mirror.

I bet you can just open the windowsand let them out. HThey are harmless to humans and the birds (or toad, snake,, mantid) would enjoy a snack.

I feel for you, I have no solutions but we get them occasionally thru the porch door when we open it to go out. Then I spend the day running around with a fly swatter because it drives me nuts.

Oh my gosh, Petalique, until your post here I’d never heard of cluster flies, how interesting!!! I love it when I learn something new! Socks needs to check hers out closely. Mine are definitely blow flies, though, with all black bodies. Yuck!

For a few errant flies or pantry moths, I highly recommend those battery operated fly swatters that resemble tennis rackets. It is very easy to target fly or moth. Very rewarding ;-)

Thank you all for the great replies.

Elmer you could be right that they are not entering but they are living in the home. We have looked all over for something dead. It could be in the attic.

Oly, yes it's "knotty pine" paneling, so yes they could be there altho' my DH says no. Your situation sounds like ours, they appear out of nowhere. I'm ordering that Zevo gadget, and we got the battery operated "tennis racket" swatter, but honestly the dustbuster is easier. But these are just instant helpers, not long term.

Petalique, I'm not at the location anymore so can't get a pic, but thinks for the instructions. I looked at blowflies, and they seem to have blue on their backs, and clusterflies don't look quite like it either. The ones we are getting are very black....maybe horseflies? Doesn't matter, I don't want 'em!!!

Lynn, sounds like you have the same flies, bigger than the ordinary houseflies, and not as quick or skitish as the ordinary ones. Easy to suck up with the vacuum, but that's an endless task.

Sorry to all of you experiencing insect invasions, and I hope your situations are solved ASP. Thank you all for the sympathy.

After reading all the problems and possible solutions here, I just now went to Amazon and ordered this bug zapper that looks like a tennis racket for my blow fly problem and others. THANK YOU, Petalique!!! I can’t stomach using the sticky pads for bugs or mice, but I think this quick zapper is something I can handle. Remember me? I’m the one who rescues tarantulas and other bugs, carrying them off to safe places outside (LOL). I don’t feel that way about flies, cockroaches, and centipedes, though! This most recent batch of blow flies is hopefully almost done for but I’ll still be ready for any other flies! Thankfully, we don’t have mosquitos up here. It must be our high mountain altitude.

Socks, when we first moved into that rental, we had a cat who loved to chase the flies and they were so slow and dopey, he had a field day - and would eat them. After about a week, I think he'd had his fill of flies and didn't even chase them any more. Since you say it's just one bedroom, is it on the sunniest side of the house? If it is, go out in the heat of the day and see if you can see them basking on the siding near that room. It might allow you to spot a place where they're getting in. That's how we discovered they were somehow getting through the shingles, but it seemed by osmosis really. We finally moved, thank goodness.

Yes, it is sunny there most of the day and yes I do see a few flies resting outside n that side of the house. Actually there was a woodpile there under the window, so I figured something died in there and spent a couple hours moving wood, but nothing dead was there. Well, maybe we'll just have to keep moving on the table (not really...lol).

LynnNM, I’m happy to hear that you let most of you insects outside. I do that as well. Mosquitoes and pantry moths are an exception.

BTW, with those electric swatters, there is no need to swat and is best is you don’t (I’ve learned). The moth or insect has to only encounter the (switched on) mesh. Those pantry moths fly around in such an erratic manner, the only was to capture them is to have this wide electrified mesh. With flies, you can just stun or kill them, then toss them outside for a bird or toad.

SOCKS! idea! You can call the entomology department of a university in that area and ask around. I’ll bet someone there will know what they are and how to best deal with that situation.

And, did you know there is a Garden Web group for Insect ID? Try them!

https://www.gardenweb.com/discussions/insect

I'm not at the location now and won't be for several weeks, but will definitely get a photo and try for ID. I did not know there is an Insect ID forum. It's sometimes hard to find the forums here. I thought there was one for pests but no luck with that.

Thanks, Petalique.

I agree it may be something dead or rotting that is hosting fly larvae. We have an attached garage, and have had what seemed like an inundation, but seems mild compared to what's being described. We used to keep the catbox out there, and lizards and geckos get in and perish too, so it could've been from any of those fly attractants.

But those electric swatters, tho great for slow moving mosquitoes and gnats or moths, have been virtually useless against fast moving houseflies, IMPE.

Also, when I finally managed to swat one - it was so big and meaty, it smelled like burnt barbecue ☹️

I've had cluster fly outbreaks twice in the past 10 years - both times in the family room addition. They are large flies and can have a kind of checkered pattern on their body. They don't lay eggs in dead vermin; they are like lady beetles and stinkbugs, looking for shelter to hibernate.

I still don't know where they entered the interior of the room perhaps through the small gaps between some of the wall paneling. The exterior walls were filled with foam insulation long ago, but I know that there are voids in that. The space between the ceiling and the roof might also be the area where they were hibernating - and then getting in through the opening for the ceiling light fixture.

Drain flies?

Not drain flies. Drain flies look like Mickey Mouse ears. "My flies" look like regular flies that come in the house in the summer, but bigger and very black. I'll get a photo next time I have a chance.

Socks, were you able to find a solution? I have a major cluster fly problem. The exterior of my house is literally covered in flies all afternoon. About a week ago I saw a bunch of flies sitting together on the stone column on the porch, maybe 20 or so, and thought it was odd that there were so many in one place. I used some Raid to spray them and to my complete shock, HUNDREDS of flies emerged from the small cracks between the stone. It was like a horror movie. Now they are all over my white, painted wood siding, all over the windows, soffit, fascia, gutters, columns, everywhere. Occasionally a few get inside but it is mostly an outdoor problem and it is driving me crazy.

Yesterday we got inundated with tiny fruit flies, even though there was no open food on the kitchen counter....Mr. Google said to put 1/4 C. vinegar + 3 drops of liquid dish soap in a shallow container & leave on a counter....works great!!

The soap is supposed to break the surface tension so the tiny flies drown....

Get them OUT of my kitchen!!.... :))

I keep a spray bottle of water mixed wirh vinegar under my kitchen sink and religiously spray my fruit , especially my bananas as soon as I bring them home from the store. With bananas, i spray coat the ends of each, as well as where they grow together. Thankfully, it’s eliminated my fruitfly problem.

* What I forgot to mention is that spraying them as soon as I get home seems to kill any eggs as well as any hidden fruit flies immediately, so they're not flying around the kitchen bothering me or procreating!

Socks, we had those large, slow moving black flies several years (5 maybe?) ago. The only place they could have been coming from is the attic and there was probably something dead, although my DH said no. We bought those clear stick tapes for the window since they seemed to congregate on the wall of doors/windows at the back of the house and on the front windows. Worked great-gone within a week or so. Happened two years in a row. Ugh. Nothing since.

I do not feel the need to save the lives of many insects. If they are beneficial, I will, and I also save the lives of spiders. I've had white flies on my hibiscus in the past, but not recently. My yellow hibiscus now has the most flowers it has ever had.

Fruit flies are particularly destructive to crops here, and beetles are destructive to forests. Ticks and mosquitoes spread diseases, and some insects have very painful stings and bites.

I do not tolerate ants in the house, and that is about all we get, except for an occasional cricket in the desert. We do get fruit flies if we leave fruit out.

For fruit flies, you can make a trap by putting some fruit inside a jar, cover the top with plastic wrap, and then poke tiny holes in the plastic. The flies can get in but cannot get out. You can also put out a dish of sweet Vermouth (which I bought by mistake once), and the fruit flies will drink the Vermouth, get drunk, and drown.

The flies just stopped coming in. we hope they won’t return next summer.

At a particular time of each year (I forget which), we have an infestation of ladybugs in one room. They don't "get in", they're already in and obviously lay eggs for the nexct year. We've cleaned thoroughly, vacuum them up, and have had the carpet cleaned. They return every year, they come and they go. I suspect you have something similar.

I get flies in the summer and finally replaced the dog-torn/chewed weather strip around the back and front doors. It didn't help. I don't know how they're getting in. Only good thing is the temperature has dropped and they are all gone.

Petilique mentioned a university class similar to what I may have taken. The class I enrolled in required lab work, we would visit local buildings, take samples, write reports.