Advice
How to get rid of flies in the house and garden
To get rid of flies in the house, find where they breed and clear it up, keep new flies out with fly screens and bins with tight lids, and deal with the few that are already inside using a fly swat or sticky fly paper. Most flies indoors are house flies drawn in by the smell of food and rubbish, or bluebottles that have bred somewhere in or near the house. A fly trap with a bait belongs outside, never indoors.
In this article
Key facts
- In warm summer weather a house fly goes from egg to adult in seven to ten days (University of Florida).
- House flies breed in manure, kitchen waste and fermenting vegetables; bluebottles in meat and carrion (University of Florida, BPCA).
- Flies carry bacteria from rubbish to food on their feet and in their gut (BPCA).
- Good hygiene, bins with tight lids and fly screens are the basis of keeping flies out (BPCA).
Jump to: which fly is it? or homemade fly traps and home remedies.
How do you get rid of flies in the house?
Take away what attracts them, shut them out and deal with the rest by hand. These five steps follow the advice of the British Pest Control Association (BPCA):
- Find the source: the kitchen bin, the food waste caddy, the cat litter tray, pet food left out, or a dead mouse or bird if you suddenly have many bluebottles.
- Clear it up: empty and clean the bin, put food waste out promptly and cover food.
- Keep the bins outside away from doors and windows, with tight-fitting lids.
- Shut them out: fly screens on windows and doors you keep open.
- Deal with the few that are inside: a fly swat or sticky fly paper.
Which flies are in my house?
The fly in your house is usually the house fly: a grey fly of 6 to 7 mm with red eyes and four dark stripes on its back (University of Florida). Large, shiny blue flies are bluebottles, and slow, dark flies gathering in the loft or by an upstairs window in autumn are usually cluster flies (BPCA).
| Fly | How to recognise it | Where it comes from |
|---|---|---|
| House fly | grey, 6 to 7 mm, red eyes, four dark stripes on the back | manure, kitchen waste, fermenting vegetables |
| Bluebottle | 6 to 12 mm, shiny metallic blue, loud buzz | meat, carrion, dustbins and rotting animal matter |
| Greenbottle | 1 to 1.5 cm, shiny metallic green | eggs mostly on dead animals (KAD) |
| Cluster fly | about 8 mm, dark grey with yellowish hairs, slow | hibernates in lofts and upper rooms; larvae live in earthworms |
| Stable fly | looks like a house fly, with a stiff, pointed mouthpart; bites (KAD) | manure and wet bedding around livestock |
More about each fly in types of flies in the UK. Only a few millimetres long? Then it is a small fly: read about small black flies in the house, such as fruit flies or fungus gnats.
Why do I suddenly have so many flies in my house?
You suddenly have so many flies in your house because something nearby is breeding them, or because it is warm and the windows are open. A house fly lays her eggs in batches of 75 to 150 (University of Florida), so one forgotten bin soon produces a new wave.
- Suddenly lots of large, shiny bluebottles: their maggots feed on meat and carrion (BPCA), so look for a dead mouse, rat or bird under the floor, in the loft or behind a cupboard.
- Lots of grey flies in summer: house flies from the bin, the food caddy, the litter tray or food left out.
- Slow, dark flies in autumn or early spring: cluster flies that come indoors to hibernate (BPCA). Read more in which fly is it?
What attracts flies, and where do they breed?
Flies are attracted by the smell of rotting and fermenting material: rubbish, food waste, manure, droppings and meat or fish scraps. That is also where they lay their eggs; house flies prefer manure, kitchen waste and fermenting vegetables (University of Florida). An open bin in the sun is a nursery for flies.
How fast do flies breed?
Flies breed fast: in warm summer weather a house fly goes from egg to adult in seven to ten days (University of Florida). The eggs hatch within 8 to 20 hours, the maggots pupate after four to seven days and the adult fly emerges two to three days later (University of Florida). Bluebottle eggs hatch in under 48 hours in warm weather (BPCA).
There is no such thing as a fly nest: flies lay their eggs straight onto rubbish, manure or a dead animal, and the maggots grow there. If you find maggots, you have found the source.
When are there the most flies?
Most flies are around in summer, because flies develop fastest in warm weather (University of Florida). Cluster flies are the exception: they come indoors in autumn to hibernate and become active again in spring (BPCA).
Are flies harmful, and do they bite?
Flies can spread germs: when a fly feeds it contaminates food with bacteria from its gut and its feet (BPCA). They walk over rubbish and then over your food, so always cover food. House flies, bluebottles and cluster flies do not bite, but the stable fly does, and its bite is painful (Cook, Insects, 2020). Stable flies breed in manure and wet bedding around livestock (Cook, 2020), so you mainly meet them near farms and stables.
What is the best way to deal with flies indoors?
The best way to deal with flies indoors is to remove the cause first: bins closed and emptied, food covered, fly screens on open windows and doors (BPCA). For the few flies that are already inside, a fly swat or sticky fly paper works.
| Measure | What it does | Our verdict |
|---|---|---|
| Bins closed, food caddy clean | removes the smell and the breeding site | the most important step (BPCA) |
| Fly screens, gaps sealed | keeps new flies out | works, as long as they stay shut |
| Finding the source | with bluebottles often a dead animal | without this they keep coming |
| Fly swat | kills one fly at a time | fine for a few flies |
| Sticky fly paper | catches flies that land on it | fine for a few flies; hang it out of reach |
| Electric UV fly killer | lures flies with light | mainly used in food premises (BPCA) |
| Fly spray | kills flies | only after screens and hygiene, and always as the label says |
| Home remedies | a smell or a homemade trap | little research, and none showing they keep flies out of the house; see the next question |
| Fly trap with bait | lures flies with smell | outdoors only, never in the house |
Do home remedies such as vinegar, a bag of water or certain smells work?
We know of no research that shows they keep flies out of the house. Vinegar with washing-up liquid, cloves in a lemon, basil on the windowsill and a bag of water by the door are often recommended; what each one does is in homemade fly traps and home remedies.
Why does a fly trap with bait belong outside and not in the house?
A fly trap with bait belongs outside because it attracts flies: indoors it draws them towards you, and it smells strongly. Bait traps for flies are meant for outdoors, away from doors, windows and where you sit, near the place the flies come from, such as the compost heap or the bins.
Use biocides safely. Always read the label and product information before use.
How do you stop flies coming into the house?
You stop flies coming into the house by giving them no food and no place to breed, and by closing the way in (BPCA).
- Keep bins away from doors and windows, with tight-fitting lids (BPCA).
- Put food waste out promptly and keep food covered (BPCA).
- Pick up dog mess quickly and do not leave pet food out.
- Fit fly screens to windows and doors you keep open (BPCA).
- Seal gaps around window frames: cluster flies gather in cracks around windows in autumn (BPCA).
Sources: British Pest Control Association, flies, bluebottles, cluster flies and PestWatch: cluster flies; University of Florida, Department of Entomology and Nematology, house fly; Cook, D. (2020), A historical review of management options used against the stable fly, Insects 11(5): 313; Dutch Knowledge and Advisory Centre on Animal Pests (KAD), flies.
