We bought our dream cabin on forty acres three years ago. We’re at our wits’ ends and are planning to sell it in the spring due to these flies. I assume they are cluster flies.
We live in southern Indiana and this is the worst they have been. They appear mainly in fall and spring when it is cool at night and warm during the day. They appear, fly around lazily, land in a window sill in the sunlight, and then die.
We thought we solved it by spraying spray foam into every ride in our metal roof in the spring. Virtually no bugs over the summer. But then today we arrived after being gone for 5 weeks or so and this is what was awaiting us. It’s not the first time it has looked like this.
We do have the cabin professionally sprayed every fall. We’ve searched and searched for entry points, but cannot find them. They appear upstairs, downstairs, north end, south end, everywhere really.
I’ve scanned Reddit so many times, I feel like there is no solution for us. The flies absolutely swarm the house on these fall days, as in on the outside too. Today it sounded like it was raining, but it was the multitude of flies running into the exterior of the house.
Is there anyone out there who has solved this?!
by Affectionate-Tea5810
38 Comments
This happened to my cabin, until I started leaving a hanging bug thing while I was away for weeks. I had fewer and fewer flies until basically none. The next year, almost none. I can’t remember the name of the thing, but it’s powerful. You have to take it out when you inhabit the cabin. I’ll see if I can find the product.
Edit: Hot Shot No Pest Strip 2
If it’s a big cabin, hang more of them.
Have you actually hired a bug professional for eval? How about the local ag department office… make sure you ID properly, get solid advice on steps to take, products or services that may help
Only use yellow porch lights, when using porch lights at all. Use black-out curtains so the interior light does not draw them.
Within eyesight of the cabin, on the far end of the property, set up a solar bug zapper with the type of light that draws bugs.
A bug zapper over a pond will feed the fish, and a bug zapper in a chicken coop will feed the chickens
I have never seen that before and am genuinely curious how this turns out.
No obvious smells like a dead animal or something? Any kind of fruit trees near the house?
Get a pet lizard.
Look under and around for dead critters or other attractants. Some times when animals can Den nearby they drag lunch and it rots or when dying they hold up in small areas. The flies then hatch and find every hole to enter inside.
Get some pet geckos, or pet finches.
Cluster Flies. They are a huge pain. My family deals with them at their cabins. They have not completely solve them. That’s mostly because they aren’t totally on top of it. This is what ChatGPT says to do. The big thing is that they will come into the house through the tiniest possible space so finding those and sealing them up as critical but then I think some of the pro preventative measures are also key.
Getting rid of them usually takes a multi-step approach: prevention, physical removal, and in some cases, targeted treatment. Here’s how to deal with them effectively:
⸻
🧹 1. Get Rid of the Ones Inside Now
Short-term control
• Vacuum them up. The simplest, safest way to remove cluster flies indoors. Empty the vacuum bag or canister right after.
• Use fly strips or electric traps near windows, attics, or light fixtures where they cluster.
• Avoid sprays inside unless the infestation is heavy — aerosols kill the visible flies but don’t stop new ones from emerging.
⸻
🪟 2. Seal Entry Points
Cluster flies enter through gaps around:
• Window and door frames
• Attic vents
• Soffits, fascia, and eaves
• Gaps around utility lines, chimneys, and siding cracks
Steps:
• Use caulk or expanding foam to seal cracks and crevices.
• Add door sweeps and tight-fitting screens on vents and windows.
• Inspect your attic and upper story — that’s their favorite overwintering zone.
⸻
☀️ 3. Treat Problem Areas in Fall (Before They Enter)
The key is prevention before they get inside — usually late August through early October, depending on your area.
• Exterior residual insecticide sprays (pyrethroid-based) can help when applied around upper eaves, soffits, and sunny south/west walls.
• Look for products labeled for cluster flies or “overwintering pests.”
• Examples: Lambda-cyhalothrin, Bifenthrin, or Deltamethrin products (brands like Tempo, Suspend, or Demand CS).
• Spray on warm, calm days before they start looking for shelter.
• If you prefer non-chemical methods, fly exclusion screens on attic vents and sealing cracks are the best long-term fix.
⸻
🏠 4. Long-Term Prevention
• Keep attic and wall voids dry and sealed; cluster flies love warm, insulated spaces.
• In spring, as they try to leave, you might see another burst — vacuum and dispose again.
• If you have recurring infestations each year, it’s worth hiring a pest control service for a fall exterior barrier treatment.
Get some spiders. Spiders are friend, also get a duster to remove spider webs.
Cluster flies maybe? A nuisance, but temporary.
Haven’t used these, but would if I was in your position, cool stuff: https://plantersplace.com/pest-patrol/control-flies-with-parasitic-wasps/
Never ever seen the northern lights…never really heard of cluster flies
You should try the TiknTok dragonflies! I haven’t done it yet but they make sense.
I think you got em all
You have dogs?
I live in a rural (but probably not as rural as your cabin) area and for the first 2 years i owned my house i got a ton of flies every warm season. By the third year there were less flies but more spiders and my wife doesn’t like spiders so she wanted someone to come out and spray for bugs. The previous owners had a guy they hired previously that they recommended so we got him to do it and sure enough every bug was dead, till next year when the flies came back. That was six years ago and I figured the spiders were doing more work than i suspected so I just left it alone and dealt with it with fly traps and suffered through it. This year I’ve seen maybe 2 flies in my house and 6 spiders and I encourage them to live on my property and leave them be when I see them (if one is inside bothering my wife I’ll relocate, not kill). The orb weavers get the majority of the flies as well as the jumping spiders. Giant house spiders and other funnel web spiders handle Beatles and ants and the cellar spiders eat the giant house spiders when they’re out cruising for booty. I also have a pond near my house that is home to lots of dragonflies that are amazing at crossing flies of the census. All this to say that spraying poison all over the place may be doing more harm than good and as long as you’re willing to live with things like spiders, wasps, mantis, and dragonflies, they will provide the pest care eventually.
It was a perfect storm for these suckers to hatch. Not just you but everyone
Not sure if this would work in southern Indiana, but I had great success with parasitic wasps for fly control when I was feeding cattle in high school. This was in Texas. I’m not sure if the same wasps would be possible to get in Indiana. They looked like little ants with wings. Nothing that is going to sting you.
Sell it to a frog for millions
Is there a crawlspace?
I feel you! We deal with tons of flies and also Japanese ladybugs. One thing to think about… if you do sell your place you should disclose the problem to future buyers or you could have legal troubles down the road. I really hope you can get it under control. I’m sure you love your place and would like to keep it!
Do you have indoor plumbing? Your p trap is a bend of plumbing that holds water to prevent sewer gases from coming in. If the water in the trap drys they could be getting in through the septic tank or they are breeding in that water before it drys out. Find out if either is happening. If the traps are drying out you get trap savers that keep it full of water. If youre not gone long enough for the traps to dry out and theyre breeding in there, cap it off.
Not in our house but in the barn we hang vanilla air fresheners , really helps keep the flies away
I was researching fly control earlier this year and came across people using Parasitic Wasps which target the pupal stage of flies and I think you release them every month or so.
Haven’t personally tried it but might be worth looking into it. Was gonna try it next year
I don’t know exactly how to go about it (there are some people commenting who seem to know), but I’m confident that you don’t have to let the flies win. They are in fact vincible.
This is going to sound crazy, but I would seriously have your cabin blessed by a minister.
If you have not already, spray any and all crevices, window frames, and door frames with Demon WP. This stuff keeps my house free of any and all insects year-round with two applications per year.
[amazon.com/Insecticide-Envelopes-Containing-Water-Soluble-Cypermethrin/dp/B002Y6DNCK](http://amazon.com/Insecticide-Envelopes-Containing-Water-Soluble-Cypermethrin/dp/B002Y6DNCK)
In the meantime while dealing with more sealing and finding a better pest control setup, leaving the window open a bit might help as from my experience they die at the windows because they are trying to get out, but of course leaving open all the time helps them get in.
We also have a fuckload of flies, mosquitoes, lady bugs, hornets etc near my home which is deep in the woods near several swaps.
– spray the lawn and bushes monthly during peak season with bifen it (also kills bees, sorry). Do this in like a 100 ft radius.
– throw “mosquito dunks” in any body of water you have access to. Even puddles.
– seal all doors and window tightly. Get quality weather stripping and even clear packing tape to put around any gaps.
– inside the house put those double sided sticky window fly traps on most windows and keep a but zapper lamp lit at night.
– try to keep the bedroom separated by a dark passage from where you enter the home, ultimately some bugs will get in at night.
– electric zapper racquets are great for when you see some and just want them dead.
you can also build bat boxes cause bats love to eat bugs
Dynatrap XL?
Create a high-pressure house so air always flows out
If you’ve got electrical power:
Screw eyehooks into each corner of the cabin, outside, under the eaves. Hang a bug zapper on each eyehook. Plug them in, watch as the pile of flies beneath each grows.
I had the same problem at one of my prior houses… it got to the point that so many flies were falling that a toad stationed itself directly below one of the zappers so he could snap up every fly that fell.
If you don’t have electrical power:
Do the same, but hang fly pest strips.
Oh yeah the buzzing, its kinda horrible lol.
But I will say my partners parents had crazy flys and these traps cleared them up in a day or so; it really did work much better than expected.
Bat box. The bats will eat the bugs.
“Nature, um, finds a way…”
Down south it’s flys and mosquitoes.
In Scotland it’s midges.
In Colorado it’s flys and mice.
Your State Ag Department will probably have useful information. Your local Bug Guy is a bandaid. Nearby farms or standing water may be driving it.
Outsmart them, overpower them, be persistent, be ruthless, and don’t expect an easy solution. Maybe it’s ten bug zappers outside, maybe it’s a positive pressure environment inside, maybe it’s filling every conceivable hole around the perimeter.
Maybe it’s hopeless and just a poor location.
Meet everyone in the area/County/etc, visit other homes and cabins, talk to everyone relevant. Call any regional Universities. Dig deep and wide.
Good luck.
Sometimes it’s better 1mile away. Sometimes it lasts a while then subsides for years. Sometimes it’s only better in some other County or State, etc.
Spiders will protect your home in a long term sustainable way. Encourage them to live near you by building habitat for them near the house outside (wood debris piles, dead hedges, understory trees, etc). Consider letting them set up webs indoors, in places that you dont mind them taking up. Flies were a major issue on my farm until I made a peace treaty with the spiders. Now flies are rare, and are eaten by the end of their 2nd day in the house.
Oh, and stop spraying insecticides. You’re killing fly predators and becoming dependent on a bug guy.
get fly trap bags and hang them on areas close enough but away from the house (they smell terrible but work really well).