Diatomaceous Earth (DE) is a natural substance used as a low-toxicity alternative to traditional chemical insecticides. Food Grade Diatomaceous Earth (FGDE) can effectively eliminate insects, provided it is applied correctly. This fine, white powder offers a mechanical method of pest control, making it a popular choice for use in and around homes. Understanding its composition and mechanism of action is the first step in effectively using this product.
Understanding Food Grade Diatomaceous Earth
Diatomaceous Earth is made from the fossilized remains of diatoms, which are ancient, single-celled aquatic organisms. These silica skeletons are mined from ancient lakebeds and processed into a fine powder. The material’s effectiveness comes from its porous structure and high silica content, typically 80% to 95% of its total composition.
The distinction between Food Grade and other grades, like Filter Grade, is based on the silica’s structure and processing. Food Grade DE is composed almost entirely of amorphous silica, which is non-crystalline and contains less than 1% crystalline silica. Filter Grade DE is often heat-treated, converting the amorphous silica into crystalline silica, a form known to pose an inhalation hazard. For residential pest control, use only the Food Grade product to ensure safety around people and pets.
How Diatomaceous Earth Kills Insects
The insecticidal action of Diatomaceous Earth is purely physical, meaning pests cannot develop chemical resistance. When a crawling insect contacts the powder, the microscopic, shard-like edges of the diatom fossils damage its protective outer layer. This exoskeleton includes a waxy cuticle layer that maintains the insect’s internal moisture balance.
The abrasive particles of the DE penetrate and scratch this waxy cuticle, compromising the insect’s defense against water loss. Once the protective oils and fats are absorbed by the porous DE powder, moisture rapidly escapes the insect’s body. This uncontrolled water loss leads to fatal dehydration, or desiccation. The process relies on direct contact with the powder, as it is not a systemic poison.
Practical Application Methods and Target Pests
Diatomaceous Earth is effective against a wide range of crawling insects that possess an exoskeleton, including common household nuisances. Pests like ants, fleas, bed bugs, cockroaches, and silverfish are vulnerable to its desiccant properties. The powder must be applied where the pests travel, not just where they are seen, to ensure they cross the treated area.
The most effective application method is dry dusting, using a hand duster or bellows applicator to dispense a very thin, almost invisible layer. A light application is preferred because insects tend to avoid walking through thick piles. Indoors, focus on cracks, crevices, wall voids, and behind appliances, where pests hide and travel. Outdoors, a fine layer can be applied around the foundation or in garden areas to create a protective barrier.
DE loses its effectiveness when wet, so it must be reapplied after rain or heavy moisture. While a slurry mixed with water can be sprayed for hard-to-reach areas, the product only works once the water evaporates and the powder residue is completely dry. For residual control indoors, the dry powder remains effective indefinitely as long as it is undisturbed.
Important Safety and Handling Precautions
Despite the “food grade” label, users must take precautions during application to protect the respiratory system. The fine dust particles, even of the amorphous silica in FGDE, can irritate the lungs and nasal passages if inhaled. Users should wear a simple dust mask or respirator when applying the powder, especially in poorly ventilated areas.
While ingestion of small amounts of Food Grade DE is not hazardous, the primary risk involves inhalation, which can lead to temporary coughing or shortness of breath. When applying around children and pets, a light, targeted application is safest, and heavy dusting should be cleaned up after pest control is achieved. Cleanup should use a damp cloth or a vacuum designed to handle fine powders, preventing the dust from becoming airborne.