Diatomaceous earth

Diatomaceous earth is a powder made from the fossilised skeletons of diatoms, tiny single-celled algae whose shells are silica. As an insecticide it is used as a dust. It is not a poison. It kills insects by drying them out: it absorbs the oils and fats from the waxy outer layer of the insect's body, and its sharp edges speed this up. It only works while it stays dry and undisturbed.

On the Australian register (APVMA PubCRIS, checked October 2026), diatomaceous earth is the only active in two stored-grain insecticides, Permaguard D-10 and Grainsave (1000 g/kg). These are used against grain weevils, beetles and moths in silos, grain stores and harvesting machinery. It is also listed as an active, alongside pyrethrin and piperonyl butoxide, in household and garden dusts. Permaguard Household Insecticide, for example, is registered against ants, cockroaches, house flies, silverfish and fleas around the home, not on animals.

The one product registered in Australia for use on dogs and cats, Permaguard Dog and Cat Insecticide, is a topical dust registered against external parasites. Its registered actives are pyrethrins (2 g/kg) and piperonyl butoxide (10 g/kg). Diatomaceous earth makes up 880 g/kg of the product, but the register lists it as a filler, not an active. So no pet flea, tick or worm treatment registered in Australia relies on diatomaceous earth as its active, and Wormy has no products listed against it.

Diatomaceous earth dust can irritate the eyes, nose and skin when it is breathed in or touches the skin, so the label directions on any dust product matter. For flea, tick and worm control on your dog or cat, ask your vet which registered treatment suits your pet.