Hey everyone,
So out of nowhere, I’ve started noticing tons of flies inside my house this week — kitchen, windows, even the bathroom. I’ve never had this problem before, and it feels like they just appeared overnight.
I’ve cleaned up, taken out the trash, checked for food left out, and still… they keep coming. I’m wondering what could cause such a sudden invasion.
A few questions I’m hoping you guys can help with:
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What attracts flies so suddenly?
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Could there be something dead in the walls or vents?
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Are there specific seasons when this happens more?
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What’s the most effective way to get rid of them fast?
Any advice (or personal horror stories) welcome — I’m losing my mind over here.
This happened to me once and it turned out to be drain flies. They were breeding in my kitchen sink overflow pipe. I poured boiling water and baking soda + vinegar down the drain a few nights in a row and that did the trick.
Check your windows and attic. Last fall I had a bunch of cluster flies sneaking in through gaps near the roofline. They hibernate inside during colder months and suddenly wake up when it gets warm again. Gross, but harmless.
If you’ve got houseplants, check the soil. Fungus gnats look like mini flies and can multiply fast if the soil stays too damp. I had to dry out my plants and use yellow sticky traps for a week.
Not to be dramatic, but sometimes a dead animal (like a mouse in the wall or attic) can cause a sudden wave of flies. Happened to us once, the smell came a few days later 
. Called pest control, and yep, there it was.
Try apple cider vinegar traps! Pour some into a small bowl with a drop of dish soap and leave it on the counter. You’ll catch dozens overnight. Totally safe and non-toxic.
It could also be a garbage can issue — even if you’re taking out the trash regularly, residue or food bits under the lid can attract flies. I deep-cleaned mine with bleach water and it made a huge difference.
I live in an apartment and we suddenly got flies after the building did plumbing maintenance. The plumber said sometimes they dislodge drain debris, which can bring them up through vents and drains. Fun times 
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If you live near a farm or have compost outside, that can be the source too. I started covering my compost bin tighter and the flies indoors disappeared within days.
When in doubt, vacuum and sanitize everything. Fly eggs are tiny and can stick to curtains or even window sills. I do a full wipe-down and use a plug-in UV fly trap, works surprisingly well indoors.
Flies reproduce fast, one unnoticed source can lead to hundreds in days. If you can’t find the origin after deep cleaning, it’s worth calling pest control for an inspection. Sometimes it’s something hidden, like a drain leak or attic nest.