Why Are There Flies in My House Suddenly?

Flies are attracted to overflowing trash cans and overripe fruit, but can easily be prevented by limiting their food sources.
Written by Heather Bernhard
Reviewed by Melanie Reiff
Flies are attracted to dirty and decaying things in your home, and can often be found around garbage cans left uncovered or fermenting fruits on countertops. You can prevent them by limiting their food supply or setting up a simple insect trap. 
Just one fly in your home can lay eggs, leading to hundreds more flies. Unfortunately, those buzzing black bugs aren’t just annoying; they can also spread disease. Whether the source is inside or outside your house, you need to figure out where they’re coming from and manage the situation. 
This simple guide will tell you everything you need to know about flies in the house and how to get rid of them, with a little help from
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Why are suddenly lots of flies in my house? 

Many common species of flies, such as the housefly or the bluebottle fly, can be found almost everywhere you live—so a sudden infestation, while annoying, isn’t out of the ordinary. 
Flies can enter your house for almost any reason, including searching for food, shelter, or water. And once they’re in, they reproduce at an alarming rate. 
Unfortunately, if you have a swarm of flies already reproducing in your home, it’s likely going to be an endless cycle. Flies get into your home, find a food source, and lay eggs. Eggs hatch in just eight to ten hours, and then (augh!) you’ve got maggots. Once the larvae turn into flies, the entire process starts over again. 
If you’re lucky, you’ll find the food source and get rid of it, eventually killing off the flies through lack of sustenance. But if you don’t figure out what they’re feeding on, you’ll need to come up with another way to control the problem. 
Pro Tip Flies aren’t just an annoying problem, they’re also dangerous to your health. According to Penn State, flies are suspected of carrying at least 65 diseases that are harmful to humans, including typhoid fever, dysentery, and cholera. 

What attracts houseflies? 

Obviously, the best course of action is to eliminate any elements that houseflies might find attractive. If there isn’t a ready food source or an attractive habitat, they may never enter your home in the first place. Still, the problem may be out of your control despite your best efforts. 
Here are some of the reasons houseflies may be attracted to your home and why you can’t get rid of them: 

Flies eat almost everything

Flies are omnivorous insects that will eat almost anything and everything. Oddly, they don’t have a mouth or teeth to ingest food, but they have a sponge-like opening that helps absorb nutrients. 
Generally speaking, they are attracted to dead or decaying matter around your house, such as fermenting fruit or an unclean litter box. Often, our simple negligence (like forgetting to empty the trash) leads to an infestation. 
Sources of food you may overlook include: 
  • Dirty and clogged drains or garbage disposals
  • Overripe fruits and vegetables left out on the countertop
  • Uncovered garbage bins in the kitchen or bathroom
  • Litter boxes that aren’t emptied often enough, or pet cages (such as hamsters or gerbils) that aren’t cleaned regularly

Flies lay their eggs near food sources

Flies need food sources to breed, both to eat and serve as the ideal area to lay eggs. Once inside your house, they will head to the dirtiest spot (typically the trash cans or a dirty drain, as mentioned above) and get down to business.
If you see maggots anywhere in your home, it is a clear indicator that your visitors have been able to reproduce. The best source of action is to get rid of their food source immediately. 

Flies depend on warm temperatures

While you certainly can’t keep your house cold as a means of pest prevention, it is important to note that you’ll likely find far more flies during the warmer months. This is because flies, much like people, tend to stay inside and hide during harsh weather and cold temperatures. 
Unfortunately, fly eggs hatch up to 2.5 times faster during warm weather than in winter months, making it even harder to control population growth. 

Flies reproduce quickly

When flies find a food source and an ideal, warm climate, what happens? They reproduce. Fast. 
Their average lifespan is only 15 to 30 days, so it makes sense that everything happens quickly. They are known to reproduce rapidly and in large numbers, potentially becoming a severe problem in just a matter of days. 
A single female housefly can lay, on average, up to 500 eggs in her lifetime, and it only takes a fly 7 to 10 days to complete the transition from egg to adult. So, for example, if you have five female houseflies in your kitchen left unchecked, they could potentially turn into 2,500 adult flies in less than a month. 
Key Takeaway Without insect control measures, a few flies can quickly turn into hundreds or thousands of unwanted pests in your home. 

How can I get rid of houseflies? 

The first step in getting rid of flies is to remove their food source. Meat, garbage, rotting fruits and vegetables, dirty drains, and pet waste are all places flies like to eat and breed. Check your home for potential food sources and remove them or clean them up as soon as possible. 
Next, a flying insect light trap or a simple strip of flypaper can complement your sanitization measures nicely. Despite eliminating food sources, you may still have a few stragglers, and a trap will help eliminate them. 
Lastly, block any entryways, such as screens with holes in them or cracks around doors, to prevent the pests from getting back in. 

How can I keep flies away from my house in the future? 

You know what they say: the best cure is prevention. When it comes to houseflies, it should be fairly easy to keep them out of your home in the future using these measures: 

Keep your house clean

Keeping your house clean through simple waste management can go a long way in preventing a fly infestation. Keep tight lids on your trash cans and empty them regularly, deal with clogged drains promptly, get rid of any old or rotting food, and keep pet waste under control. 

Block access for flies entering your house

If you don’t have window screens, installing them should be step number one. If you have window screens, ensure that there are no holes through which flies or other insects can enter. Likewise, ensure that there are no gaps around windows or doors and that any cracks in the walls or foundation are appropriately sealed. 

Properly store food and beverages

Store food in sealed containers and make sure to clean up any food or beverage spills immediately. Of particular concern are items such as meat, dairy, or produce, which can quickly spoil and become an attractive food source to not just flies, but many other insects and rodents. 

Insect traps

In a pinch, you may choose to resort to insect traps to eliminate your problem. Luckily, there are dozens of options available, and most are very budget-friendly. Some of the best choices include disposable hanging fly traps, bug zappers, or just plain old fly paper. 
Key Takeaway Eliminating a fly infestation can be as easy as emptying your trash and getting rid of rotting food. Though it may take a little while, flies will eventually die off if they do not have a food source. 

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MORE: How to remove bugs, tar, and sap from car paint
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FAQs

Flies can get in through gaps or damaged areas around window frames, door frames, and in your home's walls and foundation, or gaps around pipes.
Flies don’t nest, per se,  but they can very rapidly lay eggs and breed inside your home when conditions are right. Luckily, it’s very easy to get rid of them by eliminating any potential food sources.
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