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How to use bug spray indoors

Updated: 22 October 2026

You are standing in a kitchen with a fly aerosol in one hand and the window still shut, trying to decide whether to chase the insect or fog the room. How to use bug spray indoors, for the cans in this set, is that choice plus the time you stay out afterwards. The label on the can you received beats this outline. The [bug spray](/hub/pest-control/bug-spray) table is the product check. Shelf prices below are from 20 October 2026. Peter F., editor for DIY & tools at productscompared.co.uk, did not run a lab test. A purchase through our links can earn a commission at no extra cost to you.

You are standing in a kitchen with a fly aerosol in one hand and the window still shut, trying to decide whether to chase the insect or fog the room.

Our top picks

Raid Raid Rapid Action fly and wasp killer, 6 × 300 ml

Best overall

Raid Raid Rapid Action fly and wasp killer, 6 × 300 ml
8.2/10about £19.99
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Rentokil Rentokil Insectrol insect killer 250 ml aerosol

Rank 2

Rentokil Rentokil Insectrol insect killer 250 ml aerosol
8.6/10about £6.30
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Sanmex Sanmex fly and wasp killer aerosol, 3 × 300 ml

Best value

Sanmex Sanmex fly and wasp killer aerosol, 3 × 300 ml
6.4/10about £6.22
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On this page
  1. 1.Before you press the nozzle
  2. 2.Direct spray when you can see the insect
  3. 3.Room treatment, then air
  4. 4.After you come back in

Before you press the nozzle

Confirm the job on the can, not on the search title that got you here. Raid's six-pack and Raid's duo are indoor flying aerosols. Sanmex is a fly and wasp aerosol whose saved listing does not state indoor or outdoor, so the tin in your hand is the instruction. Rentokil Insectrol, £6.30 for 250 ml, is indoor crawling insects. Provanto is a plant trigger. PestShield is a bed-bug and flea aerosol for carpets, skirtings and bed heads. Take children and pets out. Cover or remove food, and do not aim into a fish tank or down a drain. Aerosols in this set carry flammable pressurised-container warnings, so hobs, cigarettes, pilot lights and heaters are off before you spray. If the problem is a wasp nest in the loft rather than one wasp on the window, stop. How you picked the job is the bug spray buying guide.

Direct spray when you can see the insect

Both Raid listings say you can spray the insect for fast knockdown or treat the room. Direct is the better first move when one fly or one wasp is visible and you can leave afterwards. On the duo, a short burst is credited with dozens of flies. You still do not breathe the cloud. Insectrol is the contrast. It is not sold as a seconds kill for crawling insects. Reviewers say the insect may crawl away from the treated spot before it dies. If wasps are the target, the flying titles are the ones that name them. The three multipacks are on fly and wasp killer spray UK. A wasp you cannot see, inside a wall or a loft, is no longer a direct spray.
Raid Raid Rapid Action fly and wasp killer, 6 × 300 ml

Testsieger

Raid Raid Rapid Action fly and wasp killer, 6 × 300 ml
8.2/10about £19.99
View offer

Room treatment, then air

Room treatment is the Raid option when insects are in the space and you cannot hit each one. The listing allows it. Leave with everyone else, and do not stand in the doorway to check. The saved sources, including Robert Dyas directions for Raid, tell you to ventilate. They do not print a minute count you can quote as a house rule. Flies the next day show up in the six-pack reviews when a room spray was the only step, so the bin, the fruit and the open door still matter. Insectrol's smell is strong enough that ventilation is part of the review pattern. Provanto does not belong in this room method.

After you come back in

Re-entry is when surfaces are dry and the room has been ventilated, which is the HSE line for amateur pesticides. Wipe food-contact surfaces you were not supposed to treat. Do not store a hot aerosol on a sunny sill or next to the hob. An ant that crawls off an Insectrol patch may still die away from the spot. A bed bug that is alive after PestShield is the point where more cans become the failure mode in the reviews. One buyer used twelve and then paid a professional. Six cans in the £11.99 pack do not change that pattern.

Common questions

Should I spray the insect or the whole room?
Spray the insect when you can see it. Raid's listings allow either a direct knockdown or a room treatment, and the direct reviews are the ones that describe flies dropping in seconds. A room treatment still means you leave and then ventilate. Insectrol is a poor candidate for fogging the kitchen, because crawling insects may move off before they die and the smell is already a complaint.
How long should I ventilate after fly spray?
The sources used here say ventilate. They do not give a fixed number of minutes. Follow the waiting time on the can you bought, then air the room until it is fit to breathe. Robert Dyas directions for Raid include ventilation and a stain check. Standing in the room to see if it worked is the error the choking reviews describe.
Are these aerosols safe next to a hob?
No. The aerosols in this set carry flammable pressurised-container warnings. Turn off hobs, heaters and naked flames before you spray, and do not store the can against a heat source afterwards. A quick spray over a lit cooker is the failure these warnings are for.
When can pets come back in?
When the treated surfaces are dry and the room has been ventilated. HSE garden and home advice is to keep children and pets away during treatment and until dry. These listings ask a pet question and do not answer it. A missing answer is not a yes. Fish tanks and pet bedding stay out of the spray pattern.
Will the spray stain the worktop?
The amazon.co.uk cards ask about stains and do not answer. For Raid, Robert Dyas says you check an inconspicuous place before a full treatment. Do that on a hidden edge first. Do not treat a blank FAQ as a promise that paint, stone or fabric will stay unmarked.
What if someone breathes in a lot of spray?
Leave the room, get fresh air, and follow the poisons instructions on the can. Seek medical help if symptoms continue. Do not spray again to dilute what is already in the air. The same stop applies if product is swallowed. A wasp nest or bed bugs that remain after label-rate use is a pest controller's job, not another can.

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Sources

Public UK sources used for this comparison. Shelf prices, stars and review counts are the amazon.co.uk figures captured for these six listings on 20 October 2026. Last checked 22 October 2026.

  1. HSE garden and home pesticides (retrieved 20 October 2026)
  2. HSE garden pesticide search (retrieved 20 October 2026)
  3. RHS chemical use (retrieved 20 October 2026)
  4. HSE biocidal labelling (retrieved 20 October 2026)
  5. Robert Dyas Raid directions (retrieved 20 October 2026)
  6. BPCA wasp advice (retrieved 20 October 2026)