Insect Control Powders & Dusts

They do not all work the same way. Insecticidal dusts carry an active substance and act on insects that walk through the treated layer. Diatomaceous earth works by physical action instead, with no active substance - it is only effective while dry, which makes it a reasonable choice for a dry void or cupboard base and a poor one anywhere damp. Check which you are buying on the product page.

Treating crawling insects in the places a spray cannot reach properly - cracks, crevices and voids. Depending on the product, a dust can give quick control, keep working on the treated area once it is left in place, or both. A powder is the better tool wherever you need to get into a cavity rather than coat a surface; a spray is easier on flat runs and skirting edges.

A light, targeted layer where insects travel and hide:

• Skirting edges, corners and under units
• Entry points - gaps around pipes, cracks, thresholds
• Harbourages - voids, behind kickboards, around cupboards

Do not over-apply. A thin dusting works better than piling it up, because insects walk around a heap and through a film.

A powder keeps working as long as it stays in place. Moisture, heavy cleaning and disturbance all shorten that, so reapply if the treated layer has been removed or contaminated. Diatomaceous earth in particular stops working once it is wet, so anywhere near a leaking pipe or a damp cupboard base needs drying out before re-dusting is worth doing. Follow the label guidance and wash your hands after use.

Apply them into cracks, gaps and voids where they cannot be reached or disturbed, rather than across open floor, and keep children and pets away from treated areas as the label instructs. Avoid raising dust as you apply, and do not treat food-preparation surfaces unless the label allows it. Where the range includes a food-grade diatomaceous earth, that is stated on the product page.

Check whether the dust has been walked through. Undisturbed dust means they are not using that route, so move the treatment closer to where activity actually is - monitoring traps will show you where. Dust that has clearly been crossed, with insects still appearing, means the population is larger than the treated area, so dust the remaining voids nearby rather than adding more to the same spot. And check the dust is still dry, since a damp layer has stopped working whether it looks like it or not.

If activity continues after a full treatment cycle, if it has spread beyond one room, or if you are dealing with bed bugs or German cockroaches. Look for a qualified pest controller with BPCA membership.