Flies are persistent, and once one finds its way in, more tend to follow. They're not just irritating, either – house flies and bluebottles can carry bacteria picked up from bins, drains and decaying matter, so keeping them out is well worth the effort.
The mistake most people make is going after the flies they can see while leaving the thing that drew them in untouched. Flies come indoors chasing food, warmth and light, so the most effective prevention is removing those draws and closing the gaps they get in through – not swatting. Get that right and you stop the problem before it starts.
Here are ten ways to keep flies out of your house. (If you've already got them inside, our expert guide on getting rid of flies covers clearing them out.)
📋 Quick summary: keeping flies out
- Remove what draws them in – bins, food waste, over-ripe fruit, pet mess and dirty drains are the real magnets.
- Close the gaps – fit fly screens and seal cracks around doors, windows and vents.
- Mind the light – flies head for bright lights at night, so switch to warm bulbs or turn them off near doors.
- Seal up before autumn – cluster flies push in through tiny gaps to hibernate, so proofing keeps them out.
- If some still get in – deal with the source, then the stragglers; our expert guide covers the rest.
What's Drawing Flies Into Your Home?
Flies don't turn up at random – they follow their noses to food and breeding sites. The usual draws are:
- Open or overflowing bins and food waste caddies
- Crumbs, spills and uncovered food
- Over-ripe fruit and fermenting liquids (the magnet for fruit flies)
- Dirty drains and standing water
- Pet faeces in the garden or litter trays
- A dead rodent in a wall, loft or chimney – often after rodenticide use, which is one reason we're cautious about poisons
Bright lights at night draw them in too, and in autumn cluster flies arrive looking for a warm place to hibernate rather than for food at all. Deal with the draws first, then close the doors on them.
One quick check before you start: tiny flies hovering around houseplants are usually fungus gnats from overwatering, and small flies by the sink or plughole are often drain flies – both need a slightly different fix from the common house fly.
1. Keep Surfaces and Floors Clean
The first line of defence is keeping everything clean and tidy. Keep kitchen and dining areas free of leftover food, wipe up crumbs and spillages promptly, and don't leave dirty dishes standing. Clean, scent-free surfaces give flies far less reason to come looking.
2. Use Tight-Sealing Bins
Bins are one of the biggest fly magnets, so make sure yours have tight-fitting lids, empty them regularly, and clean them with disinfectant. Just as important, site bins away from doors and windows so any flies they do attract aren't right at your entry points.
3. Store Food Properly
Don't leave food out in the open, even briefly. Store it in sealed containers or the fridge, keep fruit bowls in check and remove anything that's turning, and cover food after cooking. This keeps flies from feeding, contaminating and – worst of all – laying eggs.
4. Clean Drains Regularly
Flies, and drain flies in particular, breed in the moist, organic film that builds up inside drains and plugholes. Clean and disinfect drains regularly to remove a hidden breeding site and food source that's easy to overlook.
5. Fit Fly Screens
To let fresh air in while keeping flies out, fit fly screens to windows and doors – they're the simplest physical barrier there is. Choose a mesh with a good balance of fine weave and visibility, and keep existing screens in good repair, as flies will find any tear or gap.
6. Seal Cracks and Gaps
Screens stop flies at open windows and doors, but flies also squeeze through surprisingly small gaps – around door and window frames, air vents, extractor outlets and where pipes pass through walls. Seal these with a suitable filler or insect-proofing products, fit brush strips to gappy doors, and you close the routes screens alone can't cover.
7. Mind Your Lighting
Flies are drawn to light at night. Where you can, turn off outdoor lights near doors, or switch them to warm-yellow bulbs, which attract far fewer insects than bright white or blue-toned LEDs. Indoors, drawing curtains at dusk in peak summer – especially with windows open – stops the light beckoning flies straight in.
8. Use Natural Deterrents at Entry Points
Flies dislike certain scents, so lavender, basil, marigolds, peppermint and citrus oils all help to discourage them around doors and windows. Grow the plants on windowsills, or put a few drops of essential oil on a cloth or in a spray and refresh it around entry points every few days. They're a useful extra layer rather than a replacement for screens and sealing.
9. Seal Up Before Autumn for Cluster Flies
Cluster flies are a different problem from house flies: they don't come for food, they come to hibernate, pushing in through tiny gaps around eaves, soffits, tiles and window frames every autumn, often in large numbers. We see a lot of them at that time of year. Because they're an exclusion problem rather than a hygiene one, sealing those gaps with insect-proofing before the weather turns is by far the best prevention – once they're settled in the loft they're much harder to shift.
10. If Flies Still Get In
Even with good prevention, the odd fly gets through. For the few that do, our best-sellers are all the lower-risk options – fly trap bags, window fly-trap stickers and a pesticide-free spray like Organisect – and an electronic fly killer earns its keep in kitchens. For a full-blown infestation, our expert guide on getting rid of flies walks through the whole approach. And if DIY isn't keeping on top of it – or you've a heavy cluster fly problem in the loft – a pest controller can step in.
FAQs: stopping flies coming into your house
What attracts flies into the house?
Food smells above all – bins, over-ripe fruit, crumbs, dirty drains and pet mess – plus bright lights at night. A dead rodent in a wall or loft is a common hidden cause too. Remove the draw and most of the problem goes with it.
Why do I get flies even though my house is clean?
There's usually a source you haven't spotted – a drain, a bin just outside the back door, fruit on the turn, or a dead animal in a cavity. In autumn it may be cluster flies coming in to hibernate, which isn't about cleanliness at all.
How do I stop flies coming in through the door?
Fit a fly screen or brush strip, keep the door shut where you can, move bins away from the doorway, and switch outdoor lighting to warm bulbs so it doesn't draw flies over in the first place.
What smells keep flies away?
Flies dislike lavender, basil, peppermint, eucalyptus and citrus. Use the plants, or put a few drops of essential oil on cloths or in a spray around doors and windows. They help at entry points but won't replace screens and sealing.
Why have I suddenly got loads of flies indoors?
Usually a batch of eggs has hatched from a nearby source – a bin, a drain or a dead animal – or it's an autumn cluster fly arrival. Either way, find and deal with the source rather than just spraying the adults.
Final Thoughts
Stopping flies coming in is mostly about two things: not giving them a reason to visit, and not leaving them a way in. Keep food, bins and drains clean, fit screens and seal the gaps, mind your lighting, and seal up before autumn for cluster flies. A little regular maintenance keeps your home fly-free and protects your health and peace of mind.
We go to great lengths to ensure that all our DIY fly control products are effective, fast & easy-to-use. You may also find our expert guide on getting rid of flies useful if some have already made it indoors.
