Diatomaceous Earth (DE) is made from the fossilized remains of tiny, aquatic organisms called diatoms. Their skeletons are made of a natural substance called silica. Over a long period of time, diatoms accumulated in the sediment of rivers, streams, lakes, and oceans and these silica deposits are mined from these areas.
Diatomaceous earth is not poisonous, so it does not have to be ingested by pests in order to be effective. As insects come into contact with DE, the microscopic sharp edges pierce the insects’ skin and absorbs oils and fats causing the insect to dry out and die. The abrasiveness of DE also aids in this process. DE can remain effective as long as it is kept dry and undisturbed.
It has proven to be effective against ants, slugs, beetles, worms, fleas, mites, and almost any spider or insect, but is not much of a concern for larger creatures. Because the particles are so small, DE is safe to use around other wildlife, children, and pets.
Anyone who is particularly sensitive to particulates (such as those with asthma or any other type of breathing condition) will want to avoid directly breathing in the dust.
DE can either be dusted on to the plant and surrounding area around the roots or applied with water at a rate of 1 – 2 Tablespoons per gallon. Note that the water is only used as a carrier and the DE is most effective once it has dried on to the plant.
Even though DE is organic, the usual safer protocols for handling insecticides such as wearing gloves and a dust mask, should be followed.