Of all the pest insects out there, the house fly might be the filthiest. These buzzing nuisances are irritating, noisy, and make your home feel like a dumpster. On top of that, they can legitimately make you sick!
House flies feed on all sorts of gross things like trash, feces, and rotting food. They can easily pick up germs from these surfaces and spread them all over your home. Some of the diseases carried by house flies include salmonella, E. coli, and even anthrax.
Once you have house flies around your home, they reproduce fast. Females lay eggs in batches of 75-150 and can lay 300-900 eggs in her short lifetime. By following the steps to this guide, you can help eradicate your house fly problem quickly.
Do I Have House Flies?
While a true house fly belongs to the species Musca domestica, and that’s what will be the focus of this article. There are several families of large fly that can live in your home and all are unsanitary. Smaller flies can spell trouble too, but these are more likely fruit flies, which are easy to differentiate from house flies by their size.
Common House Flies
These are fairly easy to recognize. They are grey to black (sometimes with stripes on the thorax). Their eyes are dark red-orange, and their wings often look orange where they attach to the body.
These are a bit larger than house flies and have orange hairs on the thorax, but other than that look pretty similar to house flies. However, cluster flies tend to invade your home from the outside in autumn looking for places to overwinter, whereas house flies can be found all year.
These flies are bright blue and green, so they are very easy to spot. They may also be black but will have a more metallic texture than house flies. They develop in and around dying animals in the wild, so finding many of these flies could mean you have a dead animal somewhere in the walls or the attic.
Are House Flies Really So Bad?
Because house flies don’t bite people or cause any property damage, most people don’t consider them to be an immediate danger that they need to take care of right away. Some people view house flies as a minor nuisance that isn’t worth dealing with.
House flies love all the gross things in any home like feces, trash, and rotting food. They use the bottom of their feet to taste-test food. Then they chow down with their sponging mouthparts by regurgitating an enzyme to dissolve the food and slurping up the remains.
Between the unsanitary way they eat and how fast they breed, house flies are great at spreading diseases. Most diseases spread by house flies are enteric diseases, or food poisoning.
One scientific review from 2018 identified about 100 different pathogens that are carried by house flies, including bacteria, viruses, fungi, and parasites. Some of the commonly known ones include E. coli, anthrax, salmonella, and hookworm. Clearly house flies are something that you should try to eliminate sooner rather than later!
4 Steps to Get Rid of House Flies
Step 1: Eliminate Breeding Grounds
If you see just a few house flies, it’s possible they found their way into your home and aren’t the sign of a nearby infestation. House flies can come in from the outside through windows and doors. They’ll usually only spread about 1-2 miles from their original breeding site but can travel as far as 20 miles.
If you are seeing a lot of flies in your home, they’re probably breeding somewhere nearby, typically outside. The flies only live about a week, so it’s hard for them to accumulate in large numbers unless they’re breeding nearby.
House flies love rotting organic matter. These are the most common sources of house fly breeding grounds –
- Animal feces. If you have a pet, clean up after them often. If you scoop dog poop into a bucket, keep a lid on it and empty it weekly.
- Fermenting grass clippings. Cut your grass more often to prevent large clumps and build-ups of grass clippings that can be left behind. These piles can rot and attract flies. You may also consider bagging your grass clippings or raking them to spread them out.
- Garbage cans/dumpsters. Keep a secure lid on your garbage can and make sure the trash goes out every week. A can or dumpster lid that’s partially empty is enough room for flies to get in and breed. You may also need to wash out your garbage containers occasionally as spills can build up and get left behind by when the cans get emptied each week.
- Rotting fruit/vegetables/etc. If you’re composting organic materials be sure to keep it covered as much as possible. If you have an abandoned garden, get rid of the organic matter as soon as possible.
Step 2: Exclusion
Flies often invade homes in response to changes in air temperature. So leaks in your AC or heating will attract flies. They can squeeze in through very small openings, smaller than you might think is possible.
One of the best things you can do to keep flies out is to make sure your home is well-sealed from any leaks. Check that screen doors and windows have no torn holes (even small ones). Also, seal around window air conditioning units with a strong layer of duct tape and check it regularly. Finally, seal cracks around doors and windows with weatherstripping or caulk as needed.
Flies are opportunists that will fly in through open doors, so make sure you are closing doors behind you or install an automatic door closer if needed. If you have a garage, consider entering through it rather than directly from the outside (though make sure you close the garage door as well!)
Step 3: Set up Traps
Traps are an important strategy for getting rid of flies that are inside your home. There are a few different options to trap flies, and each has pros and cons.
You probably know light traps as bug zappers. Light traps take advantage of the fact that insects are attracted to light. The light draws the insects in, and then a deadly electric shock kills them.
Bug zappers are good general insect traps because they don’t discriminate. They will kill just about anything that flies into it. One downside to using them inside is that flies don’t see very far (only 12-25ft). They also won’t see the trap lights if the ambient lighting in your home is high, so they’re really most effective at night.
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No matter where you use it, a UV lamp is best because they are brighter and stronger. For an indoor trap, you need the strongest light you can get to compete with other light sources in your home. Replace UV bulbs about once a year, or as often as every six months for warmer states like Florida or Georgia where you have potential for breeding grounds around the home more often.
While it might seem like you should place the trap as high up as possible to get the insects away from your surfaces, traps are most effective 3-5 feet off the ground. Flies typically won’t go higher than that.
You’re probably familiar with glue traps in the form of flypaper, but they can come in other forms as well. The guiding principle behind all glue traps is pretty much the same. They consist of some flexible, mountable surface covered in a sticky adhesive and some sort of bait to attract the flies. Flies take the bait, get stuck to the surface, and die of starvation.
Glue traps are great because they don’t use any electricity, work well, and are a bit more targeted than a bug zapper because they use a bait instead of light. However, they are also hideous to look at, especially if there are not-quite-dead flies struggling on the surface. Gross!
These fly traps can be moved around as needed and out of the way if you have visitors over.
Fly bait can be put in just about anything, so there are a variety of other types of bait traps on the market. These are typically disposable.
For example, the below trap uses bait to attract flies into a bag, where they die in the liquid underneath. Most bait traps have the same drawback as glue traps – they’re ugly. They can be very effective at quickly knocking down a fly population, though. You can place them next to a breeding ground and see results fast.
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Step 4: Use Pesticides if Necessary
Most fly problems can be managed with the previous steps, but in severe cases some pesticide use might be warranted. Pyrethrin or permethrin aerosols can be used to treat an immediate problem but may not be good for repeated applications because flies have been shown to develop resistance to pyrethroid pesticides.
Flies are diurnal (not nocturnal), so they usually rest when it’s cooler at night. They rest around their breeding grounds, so you should treat trash cans, dumpsters, grass mounds, or any other surface you find many flies congregating.
Bifenthrin is a pesticide with a long residual when applied outdoors. Treat a surface once and it can last for over a month to keep flies knocked down.
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You can also treat around doors and windowsills, especially those in the shade in the hotter summer months. Flies often rest on these types of home surfaces to get out of the heat and try to find a current of cool air escaping your home.
There are also pesticide baits that you can spread around the home or mixed into water and sprayed onto surfaces. One plus side to an insecticidal bait is that it will actively attract flies as well as kill them, unlike pure pesticides.
House Fly FAQ
There are over 100 pathogens that house flies are currently known to carry, but there are likely many more. Because the diseases are carried on the feet of flies rather than only inside their body like in mosquito-borne illnesses, pretty much anything that will stick to a fly can be carried by it. Many of these pathogens aren’t associated with a single, named disease, but can cause generalized food poisoning and diarrhea. Specific studies have shown that house flies carry E. coli, salmonella, and anthrax.
Nope. Unlike some larger flies like horse flies, or even smaller flies like mosquitoes, house flies couldn’t bite you even if they tried. Their mouthparts are designed for sopping up liquids, not biting. Like all flies, they do not have stingers.
Theoretically if you could apply enough of a strong-smelling repellent to cover up the scent of feces and rotting food, you might be able to repel house flies, but this is an unrealistic endeavor. Unlike the subtle scents that attract mosquitoes to humans, the smells that attract flies are strong and nasty. You’re better off cleaning up whatever’s attracting the flies than trying to cover it up.
Yes. Nearly all flying insects are attracted to light. This is because insects use natural light sources like the moon to orient themselves, so artificial light disrupts that process. A bug zapper will work best in the dark, so make sure to turn yours on at night in your home and consider using other trapping mechanisms during the day.
It’s possible for house flies to breed in a drain if there is something especially appetizing stuck down there. In general, it’s very uncommon though. However, drain flies and fruit flies frequently breed in drains, so you may still notice flies coming out of the drain. These will be much smaller than house flies.
Well, they obviously don’t, but I can get why it appears that way. House flies breed fast and are very small, so they can seem to pop up out of nowhere either because a recent batch of larvae has just matured, or there’s some sort of hole or crack left unsealed in your home. Follow the advice in this guide and they should reduce in number or go away.
All manner of gross things – rotting fruit and vegetables, rotting meat, and feces. Pretty much any decaying organic matter is fair game. They are not picky.
Many insects in general are attracted to the carbon dioxide that we breathe out, and that includes flies. That’s why they like to land on you. This is also the way that mosquitoes are attracted to people.
In the wild, they’ll find somewhere snug to hide for the winter and go into what’s called diapause (think insect hibernation). Inside your home, it stays warm enough and flies breed fast enough that they can keep going all year round.
There’s always some debate on common names for insects, which is why scientists tend to prefer the Latin names. In this case, most entomologists would say house fly (two words) is the correct spelling. In general, common names where the insect part is a separate word indicate that the species is officially that type of insect. So butterflies and dragonflies are not true flies, but a house fly is.