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Why Do I have Small or Large Flies in My House

What has brought this flies in my house? What causes them during winter? What is the best way to get rid of them from my home? Does any of these questions sound familiar to you? Then you have landed in the right place. We’ll give you a comprehensive rundown of all that and more.


They suck. They annoy the hell out of you when they come buzzing around your kitchen or worse still land on you only to escape you when you are just about to unleash your wrath on them. They carry diseases like cholera, typhoid, and dysentery and they often seem to be getting out of hand. The question then is, “what causes flies in the house?’

Why are flies in my house?

Well, any rotting organic materials in your house can cause flies. The culprits range from food debris to wine and sugary spills (e.g. saccharin, ketchup, etc.), overripe fruits, rotting vegetables, and rotting meat.  Dirty dishes, floors, surfaces, and sinks are often a contributing factor.

Leaking drain pipes and sewers around your home can also cause invite them.

Lots of flies in house

The phrases “flies in my house”, “flies in the house” and even “lots of flies in my house” as one of our reader recently put it in the comment section of one of our articles are all too familiar in the online space. This is a true testimony to how common the age-old problem that is fly infestation is.

Read the following tips to learn how to get rid them

1. Eliminate fly breeding sites through this measures 

  • Empty the trash can regularly
  • Seal vegetable and meat scraps tightly with a polythene bag before throwing it into your garbage bin or keep them in your freezer until the day of collection.
  • Wash the drain pipes using a hard bristled brush that can be attained from your local hardware store.
  • Pour household bleach solution (1 part water:1 part bleach) into the sink
  • Keep all food materials covered and throw away or use any overripe and rotting fruits and vegetables
  •  Keep all the surfaces around your house clean and free of food debris and sugary spills. That includes the floors, countertops, sinks, kitchen cabinets etc.

2. Eliminate any potential outdoor breeding and feeding sites as follows:

  • Keep the lawn trimmed and get rid of any brush and grass heaps
  • Collect any dog feces
  • Keep birdbaths clean
  • Dispose of any dead animal properly
  • Remove any decaying wood from your yard

3. Prevent further entry into your house using the following measures:

  • Ensure that window screens fit properly and have no holes
  • Find and fill any crevices and cracks in your window frames and doors
  • Fit an insect screen over air vents

4. Fly repelling plants such as basil, lavender, and rue

These plants have fresh aromatic scents that flies simply hate. You can have a few potted plants or place a muslin bag filled with dried leaves at your doorways and windows.

5. Lemongrass spray

The fresh fragrance released by lemongrass essential oil is also unappealing to flies and will repel them away. Simply mix about 10 drops of lemongrass essential oil with 2 ounces of how water in a spray bottle and then spray the content on flies or in areas where they are often seen.

6. Sprinkle a handful of common salt

Sprinkle a handful of common salt on any fly larvae that you come across in your house.

7. Trap and/kill the adult ones

The options for trapping and/or killing them around your house range from disposable fly traps and fly papers to bug vacuums, fly lights, fly zappers, and fly swats. These commercial traps work great and are an especially powerful option for those concerned them being in your house.

8. Permethrin-containing insecticide spray

Permethrin-containing insecticide sprays are as well a good option. Just be sure to read the instructions carefully to ensure that safety is observed and the right product is chosen for your specific kind of insect.

Small or small ones

I happened to be reading around one of my favorite forums when I came across a forum community member who was concerned that small house flies were taking over his house, saying,

“Some small flies are colonizing my house. I am afraid this situation is getting out of hand and am even warier that they will soon all become adults. What should I do to get rid of this small flies in the house before hell break loose?”

This post got my attention for one reason and it is probably not what you think it is. Fly infestation is a problem that the majority of the people know only too well, but what got my attention is the fact that this forum member thinks that those “small flies in house” as she puts it are actually young ones and are yet to become adults.

On the contrary, fly develop to their full size at the pupa stage where they develop adult fly features such as legs and wings. Having emerged from the pupal case,  it ceases to grow.

This means that the “small flies in house” that this forum is not necessarily young ones. They are very likely the consequence of getting inadequate food during the larval stage of development. See more about fly life cycle here.

It is also possible that they are phorid – otherwise known as scuttle flies for their erratic movements while not in flight – as opposed to the common houseflies. The former are typically small and have long hind legs with which they stabilize themselves while flying. They are also notable for their rounded thorax.

Phorid flies have a liking for moist environments. They use rotting organic matter to reproduce and are often see around clogged drains, in trash cans, in kitchen sinks and cabinets, on overripe fruits, and in broken sewers, and in potted plants.

Your best of action in getting rid of them is to clean your drains and sinks with household bleach and a stiff brush to get rid of any accumulated organic debris (where they could have laid eggs) before tracking down and killing any adults with a fly swat, fly trap, bug vacuum, or fly trap. It is also a good idea to keep all foods covered or refrigerated.

In winter

“I have noticed an upsurge of flies in my house this winter. These flies seem bigger than the common houseflies and tend to swarm around windows. How do I get rid of them?” Maryann

High chances are that these are cluster flies. They look very similar to common houseflies but they are typically larger. They are often spotted inside the house in fall and winter and have a notable sluggish flight. They are semi-dominant and have a unique life cycle that is totally different from that of a housefly.

The cycle starts with the female laying eggs in the soil during spring. The hatched larvae feed on earthworms. Several generations are brought forth during summer. By late summer,  they start seeking overwintering shelter by flying into buildings in the afternoons where they rest on the sun-exposed sections.

At sunset, these flies then seek out cracks and move into the buildings, preferring the upper stories. Come sunny warm winter days, they become active. They tend to hover about windows.

The best management option for this problem range from fly swats to permethrin-containing insecticide sprays (but read the instructions carefully), bug vacuums, and cluster fly traps. It is also advisable to caulk or fill any cracks and openings in your window frames and doors and install insect screens over air vents as part of your infestation management regime.

Large flies in House

“Hi. I have recently noticed large, black-colored and lazily-moving flies in the house. Today I swatted more than 20 of them over a span of just one hour. They tend to hover around the windows. My house is clean and there are no broken drains or sewers, so I don’t think it has anything to do with dirt. What should I do about them?” Veronica

Well, you are very likely dealing cluster flies. While they resemble common houseflies, they are typically larger-sized. They are often seen around homes during fall and winter.

Swatting cluster flies (using a fly swat) is rather easy since they move around slowly relative to common houseflies. Just be sure to clean the surfaces and walls of the bloody mess left behind as they can stain surfaces. You may also want to invest in a bug vacuum or get yourself a cluster fly trap. Spraying them with a pesticide is as well an option.

Best to kill or get rid of them

“I have an abundance of flies in my house. I just wish they could fetch me some dollars as that would most definitely make me richer. Just kidding. Anyway, what is the best way to get rid of flies in house?” Suzie

This question was posed to use by Suzie, one of our frequent commenters in another site on our network. The best way to get rid of flies in your house is to combine an elimination of breeding sites and larvae with killing of the adult flies.

Common culprits in as far as fly breeding sites are rotting food debris, vegetables, and fruits; dead animals; dirty and leaking sinks, drains, and sewers; and uncovered and/or stale foods. We have covered the intervention measures for this fly attractants in more details in a previous section of this guide.

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