Flea Killer Powders

Most work by physical action rather than by poisoning. They only work while dry, so a powder that gets damp, is walked in, or is vacuumed up stops working - keep treated areas dry and undisturbed, and reapply after cleaning.

Into the gaps a spray runs off: skirting joints, floorboard cracks, under and behind furniture, and the edges of carpet where it meets the wall. Also treat pet resting areas and under sofa cushions where the label allows it. Apply a fine, barely visible layer - a thick deposit is more likely to be walked out of place or vacuumed away than a light one.

Used correctly, powders including food-grade diatomaceous earth can be suitable for homes with pets and children. Apply sparingly into cracks and crevices out of reach, avoid raising dust while applying, and keep it dry and undisturbed. Follow the label directions on the individual product.

After vacuuming, after cleaning, and any time the treated area has been dampened or disturbed. Powders are not used up as they work - they simply stop working once they are no longer dry and in place, so reapplying is about restoring the layer rather than topping up a dose.

Two different pictures. If the powder is still visibly in place and undisturbed, the issue is coverage: fleas are living in open carpet and soft furnishings where a powder cannot sit, so a flea spray is needed for those surfaces alongside the powder in the gaps. If the powder has been walked in, vacuumed or dampened, it has stopped working and needs reapplying to dry, undisturbed areas.

Both, in most cases. A spray covers the large soft surfaces where flea eggs and larvae actually sit. A powder holds in the narrow gaps a spray cannot coat and stays there as long as it is dry. Using one without the other usually leaves half the population untreated, which is why our flea control kits pair them.

Falling numbers rather than an immediate stop. Comb the pet, or walk across the treated carpet in white socks, and repeat the check weekly - fewer fleas each time is the signal. Expect two to three weeks before the checks come back clear, because eggs and pupae keep hatching after treatment begins.