Diatomaceous Earth (DE) is a fine, powdery substance derived from the fossilized remains of diatoms, which are ancient, single-celled aquatic organisms. This powder is composed primarily of amorphous silica, and its effectiveness as a pest control or filtration agent stems from its physical properties. The microscopic particles act as a desiccant, absorbing the protective waxy outer layer, or exoskeleton, of insects, which causes them to dehydrate rapidly. Since specialized dusting equipment is not always available, alternative household methods can effectively apply this product.
Essential Safety Precautions
Handling powdered DE requires specific safety measures, as the fine particles can easily become airborne and cause irritation. It is important to wear a dust mask or a respirator to prevent inhaling the powder, which can be irritating to the respiratory tract. Eye protection, such as safety goggles, should also be worn to protect the eyes from the abrasive dust.
You must also distinguish between the two primary grades of this material before any application. Only food-grade DE should be used in areas accessible to people, pets, or livestock, as it contains amorphous silica and is non-toxic. The other form, filter or pool-grade DE, is heat-treated (calcined) and contains crystalline silica, which is hazardous if inhaled and should never be used for pest control or around the home.
Applying DE as a Wet Slurry or Spray
A highly effective way to apply DE without a duster is by creating a wet slurry, which allows for precise application on vertical or hard-to-reach surfaces. A common and effective ratio for this mixture is approximately four tablespoons of DE powder for every gallon of water. The powder does not dissolve but rather remains suspended, so constant agitation is necessary to prevent the silica from settling at the bottom of the container.
This liquid mixture can be applied using a standard garden pump sprayer, provided the nozzle is wide enough to avoid clogging from the fine particles. Using a sprayer without fine filters is often necessary to ensure a smooth application. For smaller, more targeted areas, such as into crevices, cracks, or along the undersides of plant leaves, a simple paintbrush can be dipped into the slurry and used to brush the mixture onto the surface.
When applied as a wet slurry, the DE is completely ineffective against pests until the water fully evaporates. Once the moisture is gone, a thin, white, dry residue of the abrasive silica particles is left behind, which begins its desiccating action on any crawling insect that crosses the treated area. This method is particularly useful for outdoor areas where dry powder might be blown away by wind.
Dry Application Using Household Tools
For dry surface application indoors or in protected outdoor spaces, various common household items can substitute for a specialized bulb duster. A simple flour sifter or a fine-mesh sieve provides an excellent way to broadcast the powder over larger, flat surfaces like carpets or garden beds. The sifting motion helps to distribute the material in a light, even layer, which is crucial for efficacy.
For targeting smaller cracks, crevices, and wall voids, a clean, dry salt shaker or a large spice container with a perforated lid can be used to apply a fine line of powder. The goal is always to apply a layer so thin that it is barely visible to the eye. Pests will avoid thick piles of the powder, making the application ineffective.
A simple scoop, such as a measuring cup or small trowel, is suitable for broadcasting the powder over large, flat areas, such as concrete slabs or the perimeter of a structure. Regardless of the tool, remember that the DE must remain dry to maintain its effectiveness, as its mechanism relies on drawing moisture from the insect’s body.
Incorporating DE into Soil and Feed
Diatomaceous Earth can also be mixed directly into bulk substances, bypassing the need for surface dusting. For gardening, incorporating the powder into potting soil or garden beds helps to control subterranean pests, such as fungus gnat larvae or root-knot nematodes. A general guideline is to mix the DE at a rate of 15 to 30 percent by volume into the soil to ensure adequate coverage and aeration benefits.
This amendment not only works to control soil-dwelling insects but also improves the soil structure by increasing water retention and drainage due to the highly porous nature of the silica particles. For internal parasite control in livestock and pets, food-grade DE can be mixed directly into feed. A common recommendation for this application is to incorporate the DE at a rate of up to two percent of the total dry feed weight.