Why Are There So Many Flies in My House? (2024)

Flies are scavengers that feed on dead and decaying matter. While they typically live outdoors, they're occasionally spotted indoors when they enter a home to find food, shelter, or water. If you're noticing a lot of flies inside to the point that you're asking, "Why are there so many flies in my house?" you've got cause to be concerned. When lots of flies suddenly appear in your home, it can lead to the spread of pathogens that cause disease and other infections. There are ways to eliminate a fly infestation and prevent the bugs from returning, but first, you should understand the cause of the sudden influx of pests.

Why Are There So Many Flies in My House?

Common fly varieties include houseflies, fruit flies, drain flies, and blue bottle flies. The species spotted in your home depends on where you live and the environmental conditions inside your house. As for why there are so many flies in your home, there are several potential reasons for a sudden influx.

Decaying Matter

Most flies feed on organic matter. They hunt for food on countertops and in trash cans, compost piles, and stagnant water. Fruit flies feed and breed on rotting or overripe fruit. Drain flies feed and breed on organic matter in your drains or pipes. So, the sudden increase of flies in your home is likely due to the presence of decomposition. If you can't see the source, you may have a dead rodent inside your walls or under your floors.

Warm Temperatures

Flies thrive in warm temperatures of 75°F and higher. Their larvae can mature in 4 to 13 days. Keeping the indoor temperature cool can ward them off and delay larvae hatching.

Rapid Reproduction

Most fly species reproduce quickly. If you spot one or two flies today and don't get rid of them quickly, you might be dealing with an infestation in a few days. The average lifespan of most flies is between 15 and 30 days, depending on factors like food availability. Female houseflies can lay as many as 500 eggs during their short adulthood; it takes only 7 to 10 days to complete the life cycle from egg to adult. So, if you spot five female flies in your kitchen, you could have an infestation of over 2,000 adult flies in less than a month.

Measures to Prevent and Control Fly Infestations

If you're asking yourself, "Why are there so many flies in my house?" chances are you already have a fly infestation. Destroying their breeding grounds is the best way to eliminate them. Depending on the fly species, breeding grounds vary, so correctly identifying the fly species you are dealing with is helpful. After you get rid of the flies, you'll want to take measures to prevent re-infestation.

Keep a Clean House

Vacuum, sanitize all surfaces, and clean utensils to eliminate any potential food sources. Also, regularly flush and clean plumbing pipes because they are ideal breeding sites for drain flies.

Eliminate Potential Breeding Grounds

Compost piles, clogged dish drains, uncovered trash cans, leftover food, and waste can quickly become breeding grounds for flies. Make sure all trash cans are covered. Empty them regularly and clean them thoroughly—inside and out. Clean and remove pet waste immediately. Also, keep pet feeding bowls clean and dry.

Prevent Access

Typically, flies live outdoors. However, they access your home through doors and windows. Take measures to keep them out, such as ensuring the door and window screens are not damaged. Seal all crevices and install weather stripping around entry points. Use caulk or foam to seal any openings, especially where pipes come through the exterior of your home.

Store Food Properly

Place food in sealed containers and promptly clean any food or beverage spills. Adequately cover leftover food and store it in the refrigerator. Dispose of overripe fruits and cover all trash cans. All food attracts flies, other insects, and rodents, so it's important to literally and figuratively cover every base.

Call an Exterminator

Contact a professional if you have an infestation you cannot get rid of. Professionals can correctly identify the flies and eliminate their breeding grounds.