How Do Flies Get Inside A House When Windows Are Closed? (Explained)

how do flies get inside a house when windows are closed

Flies in your home are a nuisance, and we were taught from a young age to keep the windows closed if we don’t want pesky flies invading our territory! However, sometimes keeping windows closed is not enough to ward these pests off.

If you have seen house flies in your home even when the windows are closed, you are probably feeling hopeless and overwhelmed, even if it’s just a few stray flies. So, how do flies get inside your house when windows are closed? Keep reading to find out!

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How Do Flies Get Inside A House When Windows Are Closed?

Flies are not only annoying pests, but they can also be harmful to your health! Flies carry diseases like salmonella, tuberculosis, and cholera. Because of this, it is important to understand how flies are getting into your home so you can take care of the problem.

Here are the most common reasons why flies may be getting in your home even when the windows are closed.

1. Door Traffic

One of the main reasons flies are getting into your home when the windows are closed is because you may have a lot of door traffic. If you and other people consistently go in and out of a door, this is prime time for flies to enter your home.

Even if you are not leaving the door open for a long time, they can still find a way to creep in.

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2. You May Have An Open Window That You Didn’t Know About

You May Have An Open Window That You Didn't Know About1

Image Credit: Life As A Human

This may be obvious, but if flies are getting in your house even when the windows are closed, you may actually have an open window.

There are times when we open windows to let out any smells or orders that may be inside, especially when we are cooking dinner and accidentally burn something, and we forget to shut them.

It would be a good idea to check all of your windows to make sure they’re all actually closed, just in case!

3. Through Cracks and Crevices

Another way flies may be getting into your home is through cracks and crevices n your home! You may not think much about cracks or open spaces in the window sills or walls, but flies and other bugs will jump at the opportunity to make their way through these little spaces.

They can also find their way in through the vents in your home! Yikes!

4. Through Your Plumbing

Through Your Plumbing1

Image Credit: Terry’s Plumbing

You may think that water kills flies, but you should think again. Some types of flies, such as drain flies, can make their way into your home through pipes!

5. Damaged Screens

Damaged screens are also a cause for concern when it comes to flies getting into your home. Sometimes, you get small rips and tears in your screens, and you don’t know it. Make sure you check your screens thoroughly for any signs of damage.

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6. Hatched Fly Eggs

If you have made sure all of your windows and doors stay closed, another reason flies always seem to be in your home are breeding flies somewhere hidden.

Flies reproduce quickly, laying about 500 eggs in only three to five days! When the eggs hatch, they release the fly larvae, which are also known as maggots. Maggots are tiny and resemble a grain of rice and inch their way along surfaces similar to caterpillars. From the maggot stage, they grow into what we know as gnats, then to fully grown adult flies.

There are certain conditions in which flies love to breed and lay their eggs. One of the main places in dark areas with a lot of moisture! Check under your kitchen and bathroom sinks to see if you have any leaky pipes, as this is one of the main areas you are likely to find fly eggs, maggots, or gnats!

Also, check your attic, basement, inside garbage cans, and potted plants to see if you can spot any fly breeding activity.

You should also note dirty dishes in the sink can also be problematic if they are left for too long.  Flies are attracted to rotting food and debris. If you have been busy and haven’t tended to the dirty dishes in your sink, you should check to see if you see any maggots there.

How To Get Rid Of Flies In Your House

Now that you know some of the reasons flies are in your home, now it is time to take care of the issue! Here are steps you can take to get rid of flies and keep them gone:

1. Seal Any Cracks

If you have any cracks in your window sill or walls, you will want to seal these immediately! You can find caulk at any hardware or home and garden store, and it’s very simple to use.

Just read the manufacturers on the back of the caulking tube for specific directions for the type of caulk you are using. Here is a video on how to choose the right caulk for your project.

2. Put Screens On Your Windows and Doors

If you do not already have screens on your doors and windows, this should be a top priority! Screens help prevent flies and other insects from getting in your house when the doors and windows are open.

This means if you open a window to let some fresh air in, you won’t have to worry about flies coming into your house, even if you forget to close it.

If you already have screens, but they are damaged, it would be a good idea to replace them!

3. Eliminate Any Fly Eggs Or Maggots

If you discover fly eggs or maggots anywhere, you need to get rid of them ASAP!

You first need to kill the maggots. You can do this with vinegar or bleach. Bleach kills maggots almost instantly, while vinegar takes a little longer. You can also opt for a chemical spray such as pyrethrin sprays.

Once the maggots have stopped moving, you should vacuum them up with a vacuum cleaner. Alternatively, you can wipe them all up with a paper towel, but this takes a lot longer and is a lot messier.

Always remember to wear good gloves when taking care of fly eggs or maggots.

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4. Use A Natural Fly Repellent

Use A Natural Fly Repellent1

Image Credit: Maid2Match

Another step you can take to get rid of flies and keep them away is to use a natural repellent, such as essential oils!

Lavender, peppermint, eucalyptus, and lemongrass are all great essential oils known to repel flies. You can diffuse the oils into the air with a diffuser or make a room spray with distilled water, witch hazel, and essential oils.

You can also place an essential oil-soaked cotton ball near your windows and in your vents. If you want to buy only some of these oils separately, they make pre-made essential oil blends meant to repel bugs.

5. Use Traps

Traps are another great way to take care of your fly problem! A Venus fly trap plant is a great option if you want a natural fly trap. This plant actually eats flies, so it will help you keep them under control. Just be sure to give it plenty of water and take care of it accordingly.

They also make commercial fly bait traps you can hang up near your home. These traps hang from the ceiling and attract flies into it, then kill them by drowning them in the solution.

Just keep in mind that the fly bait traps get smelly after a while, so you will want to replace them often.

6. Call A Professional

Lastly, if you have a major fly infestation, you should probably call Pest control to take care of the issue for you. Some jobs are too big for just one person, and you will save a lot of time, money, and peace of mind to have someone else take care of the problem for you.


Flies are a problem enough when they are outside, but when they come into our homes, it can be disastrous! There are many reasons flies can get into your home even when the windows are closed, so it’s important to check your home for places they may be finding their way inside.

Once you figure out where they are coming from, make sure you take the proper steps to take care of the problem so you or your family don’t suffer from any fly-related health issues.

Have you dealt with flies mysteriously showing up in your home? How did you handle it? We would love to hear about it in the comment section below. We love to hear from our readers.

We hope you enjoyed this article! Thanks for reading!

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