Crawling Insect Control Products

Worth ten seconds before you buy anything. Silverfish are carrot-shaped, silver-grey and move in a wriggle; woodlice are grey, armoured and trundle or roll - both point at damp rather than food. Carpet beetle larvae are small and hairy and turn up in wool, carpet edges and wardrobes, not the kitchen. Cockroaches are flat and fast and shelter somewhere warm near food or water. Ants you will see in a line. Getting this right matters because the treatments differ: read our guide to chemical and physical insect treatments for how the product types compare.

Work in order rather than reaching for a spray first. Close the way in - gaps under doors, around pipework, vents and airbricks - with insect proofing products. Put out monitoring traps so you can see where activity actually is. Then treat those places: bait where the insect carries it back to a nest, a spray or powder where it does not. Treating before you know the routes is the commonest reason a first attempt achieves nothing.

The range runs from sealed bait stations to insecticide sprays, so it depends what you buy. Enclosed baits and traps keep the active substance contained and are the lower-risk choice in an occupied room. With sprays and powders, keep children and pets out during application and until treated surfaces are dry, ventilate as you work, apply into cracks and voids rather than across open floor, and do not treat food-preparation surfaces unless the label allows it. Follow the label directions for the specific product.

Some, but not all - check the label on the product page, because a product approved for indoor use is not automatically approved outdoors. Where outdoor treatment is permitted, a barrier at doorways, thresholds and airbricks is usually more use than treating the garden generally, since the aim is to stop insects crossing into the building rather than to clear ground.

Yes, and most jobs need to - but not on the same spot. Spraying over or beside bait puts insects off feeding, and feeding is what carries the treatment back to a nest. Bait the harbourages, treat the routes and cracks around them, and keep traps running so you can see whether numbers are falling.

Which of these are you seeing? If bait is being taken but numbers are unchanged, it is reaching foragers and not the nest, or it is the wrong bait for what the colony is feeding on at the moment. If bait or powder is untouched, you are not on their route - move the treatment to where the traps are catching. If you knocked insects down and more appeared within days, only the ones out in the open were treated and the harbourage was never reached.

Something is still letting them in or keeping them comfortable. Check the way in first: gaps under doors and around pipework, airbricks, vents and window frames. Then check for damp, which is what silverfish and woodlice are actually after - a leaking trap, condensation, a blocked gutter running down a wall. Then check what is being carried in, since carpet beetles and cockroaches often arrive in packaging, second-hand furniture or through a shared wall. Our guide to insect proofing a home or business covers the gaps worth closing.

Leave one or two monitoring traps set after you stop treating and check them weekly. Two to three weeks with no fresh catches and no new sightings is a reasonable all-clear. Activity reappearing at the same point next year usually means the way in was never closed rather than that the treatment failed.

If activity is still there after a full treatment cycle, if it has spread beyond one room, if you have bed bugs or German cockroaches - both hard to clear as a DIY job - or if there are vulnerable occupants in the property. Look for a qualified pest controller with BPCA membership.