How to get rid of mosquitoes, indoors and out: what works, and what only looks like it does

The reliable way to reduce mosquitoes indoors and out is not a product. It is two habits: remove the standing water they breed in, and put a physical barrier between the insect and your skin. Everything else, from repellents to coils to gadgets, ranges from a useful supplement to no measurable protection. If you do only the two habits, you will have fewer mosquitoes than a neighbour who buys everything else.

That is the whole answer, and the rest of this guide explains why. The mosquito-protection aisle sells a great deal of confidence and little protection, and this guide sets out the evidence for each product class.

How mosquitoes breed, and why the water matters

A mosquito's early life happens in water. The female lays her eggs in or beside standing water; the larvae live in it; only the adult flies. This is why the water matters. No adult mosquito exists without a small pool of still water somewhere nearby.

The container-breeding species that now dominate European towns, above all the Asian tiger mosquito, will use astonishingly little of it: a flowerpot saucer, a bucket, a discarded toy (US CDC, preventing mosquito bites). The tiger mosquito also rarely flies more than a couple of hundred metres in its life. The ones biting you were almost certainly bred within sight of where you are standing.

That single fact is the good news. You do not have to clear a region of mosquitoes. You have to clear your own few square metres, and you have far more power over that than any spray does.

How to get rid of mosquitoes outside

1. Empty every container of standing water, once a week. This is the most effective single action, and it costs nothing.

Walk your garden, balcony or terrace once a week and tip out anything holding water, then scrub it, because eggs cling to the sides above the waterline and survive a simple pour-out. The usual suspects:

• plant saucers and pot trays
• blocked gutters and downpipes
• watering cans, buckets and wheelbarrows
• children's toys, sandpit covers, tarpaulins and folds in pool covers
• birdbaths (refresh weekly), pet bowls, and the drip tray under an air-conditioning unit
• old tyres, and any forgotten container behind the shed

For water you cannot remove, such as a water butt, fit a fine mesh cover so females cannot reach the surface to lay. This one weekly walk does more than every gadget on this page combined, because it removes the next generation before it can fly.

2. Put barriers where you actually sit and sleep.

You cannot screen a whole garden, but you can screen the places you spend time. Fitted insect screens on doors and windows keep mosquitoes out of the house entirely; a netted enclosure protects a patio, a bed or a pram. The mesh has to be genuinely fine, because the tiger mosquito is small and a coarse weave built for larger night-flying mosquitoes lets it through, a failure we set out in detail in how to tell a net that works from one that only looks like it does and in screen doors and windows.

3. Know what the yard gadgets actually do.

These are the products people reach for first, so it is worth knowing what the evidence says.

Bug zappers do little against mosquitoes and harm other insects in the garden. The American Mosquito Control Association summarises the controlled studies: mosquitoes made up only 4.1% and 6.4% of a zapper's daily catch over an entire season, and there was no significant difference in mosquito numbers in yards with a zapper and yards without one (American Mosquito Control Association FAQ). The insects a zapper mostly catches are moths, beetles and other harmless night insects, including pollinators and insects that feed on mosquitoes.

Ultrasonic repellers, the plug-in boxes and phone apps that claim to drive mosquitoes off with sound, do nothing measurable. The same association reports that at least ten studies found ultrasonic devices have "no repellency value whatsoever" (AMCA FAQ). It is one of the most thoroughly disproven consumer products in the category, and it keeps selling.

Foggers and space sprays reduce the adult mosquitoes that happen to be flying at that moment, then wear off. They do not touch the larvae in the water, so the population refills within days. Repeated use also drives insecticide resistance and harms pollinators and other beneficial insects. A fog lowers adult numbers for a short time. It does not address the breeding water, and that water is what keeps producing mosquitoes.

If a still evening on the terrace is the problem, a simple outdoor fan helps more than most of these: mosquitoes are weak fliers, and a steady breeze across a seating area genuinely makes it harder for them to land on you.

How to get rid of mosquitoes inside the house, naturally

"Naturally" usually means "without spraying chemicals in my home," and the good news is that the most effective indoor methods use no chemicals at all.

1. Find the indoor water. Mosquitoes breed indoors too, in the saucer under a houseplant, the tray of a self-watering pot, a vase of cut flowers left too long, a rarely used sink or floor drain, a dehumidifier reservoir. Empty and refresh these, and the indoor supply of new mosquitoes stops.
2. Screen the openings. A fitted screen on the windows you open is the single best indoor measure, because it stops mosquitoes entering rather than catching them once they are in.
3. Protect the bed. A correctly specified net over the bed is the oldest and still one of the most reliable methods there is: it removes the bite where you are most exposed and least able to swat, and it uses nothing but fabric. A ceiling or bedside fan does double duty, cooling the room and disrupting the mosquito's approach.
4. Deal with the one already in the room. When a mosquito is loose indoors, low-tech methods work best. Turn off the lights, use a torch or phone screen to find it resting on a wall, often low and in a shaded corner, and remove it.

Notice what is not on this list: no coil, no plug-in, no ultrasonic box. They are absent because the methods that work indoors are barrier and source-removal, and the chemical devices bring tradeoffs that the barrier does not.

What repels mosquitoes on the skin, and what does not

For the skin a barrier cannot cover, use a proper repellent and know what it is for. Repellents containing DEET or picaridin work, and both are among the active ingredients the US EPA has registered for skin application (US EPA, skin-applied repellents). Head-to-head trials found DEET gave the longest complete protection (Fradin and Day, New England Journal of Medicine, 2002). IR3535 and refined oil of lemon eucalyptus (PMD) are also recognised active ingredients.

These are effective, and they are a supplement rather than a barrier: protection ends the moment you forget to reapply. Use them on exposed skin during the hours a screen cannot cover, as a top-up rather than a replacement for a barrier. We spell this out in DEET and picaridin: effective, but not a barrier.

What does not reliably repel mosquitoes is the home-remedy shelf. Repellent plants such as citronella or lavender release too little active compound at any useful distance to protect you, and home-made essential-oil sprays lose what little effect they have within minutes. Public-health bodies are explicit that the effectiveness of unregistered natural products is unknown, so they are not the thing to rely on (CDC Yellow Book).

Products the evidence does not support

These products are sold as protection. Here is what the evidence shows for each:

• Mosquito coils burn an insecticide indoors along with a great deal of smoke. One study found a single coil can release as much fine particulate (PM2.5) as burning between 75 and 137 cigarettes. That is a real respiratory tradeoff for a small effect (Liu et al., Environmental Health Perspectives, 2003). More on this in what is actually in a mosquito coil.
• Citronella and scented candles provide scent, not measurable outdoor protection. The comparative repellent research puts their real-world protection close to nothing (Fradin and Day, NEJM 2002). See do citronella candles work.
• Plug-in vaporisers release a continuous, poorly characterised chemical load into sealed rooms in exchange for convenience: plug-in vaporisers in sealed rooms.
• Bug zappers and ultrasonic devices are covered above: one catches mostly non-target insects, the other does nothing measurable (AMCA FAQ).
• Uncertified marketplace nets are the clearest case. A barrier is the right idea, but a coarse-mesh, unrated, unauthorised net with gaps lets the mosquito through and gives little protection (uncertified marketplace nets).

None of these is a scandal in isolation. Together they explain why so many households spend money every summer and still get bitten: the money goes into gadgets and skips the water and the barrier.

What we know

The one rule that puts it all in order

If you remember one thing, make it this: no spray removes the water that breeds the mosquitoes. No coil, fog, zapper or candle drains the saucer of water that is making the mosquitoes. Only removing the water does that, and only a barrier keeps the survivors off your skin. Put your first hour of effort into the standing water and the screens, add a proper repellent for exposed skin, and leave the gadgets on the shelf.

If the mosquitoes around you bite in daylight and go for your ankles, read the Asian tiger mosquito guide next, and if you are already dealing with the bites, why mosquito bites itch and how to stop it covers the aftermath. You can also check how far the tiger mosquito has spread in your region on the tiger mosquito threat map.

Sources: ECDC Aedes albopictus factsheet | American Mosquito Control Association FAQ | Fradin and Day, NEJM 2002 | Liu et al., Environmental Health Perspectives 2003 | CDC Yellow Book | US EPA, Skin-Applied Repellent Ingredients | US CDC, preventing mosquito bites

This article is general information, not medical or pest-control advice. For an infestation or a disease concern, consult a qualified professional.