To use diatomaceous earth, lightly dust it onto areas where pests are a problem, and then reapply the substance after every rainfall or heavy dew. Only use food-grade diatomaceous earth to kill pests.
- Apply diatomaceous earth to the soil
To control flea or tick infestations, apply a light dusting of diatomaceous earth to your lawn. Dust chicken coops, dog pens and other animal enclosures, since many parasites live in animals' digestive systems. Sprinkle diatomaceous earth on the soil of your garden and under the leaves of large plants such as squash. Dust the substance directly onto plant leaves if desired, but avoid covering blooms where pollinators are present, since doing so also kills beneficial insects.
- Reapply diatomaceous earth after rain
To keep diatomaceous earth effective, reapply it every time the soil gets wet. Dust the infested areas after each rainfall, after heavy dew, or after watering the lawn.
- Use diatomaceous earth for indoor pests
Apply diatomaceous earth to indoor areas where roaches, fleas and silverfish like to hide. Using a bulb duster, puff the substance into hard-to-reach corners and crevices. Use a broom to sweep diatomaceous earth into the cracks of wood floors and under furniture to kill pest eggs.