It acts as a stomach poison and is relatively non-toxic to mammals. If kept dry, boric acid dust remains effective for long periods of time. When applying boric acid dust, wear a dust mask to avoid breathing the material. Use a bulb duster to apply a light dusting in cracks and crevices. This is recommended over dusting large, open areas.
Boric acid is approved for crack and crevice treatment in kitchen and food preparation areas.
Boric acid can be dusted into wall voids and spaces behind and under cabinets. These are insecticidal dusts that can be used for ant control. Diatomaceous earth is made from fossilized diatoms, and silica gel is produced from sand. Diatomaceous earth and silica aerogel are especially useful in wall voids and similar closed spaces. During construction and remodeling these dusts can be blown into such spaces, and in finished buildings they can be applied by drilling tiny holes in the walls.