Natural/Organic Dust Insecticides

- Effective, low toxicity alternatives -

Summary: Several natural insecticides that are formulated as dry powders or "dusts" can be used in a wide variety of pest control situations. These dust insecticides are both highly effective and relatively safe when used correctly.

Jack DeAngelis, PhD
OSU Ext. Entomologist (ret.)

What is a natural dust insecticide?

Insecticides are available in a variety of different forms, or formulations. Some, for example, are liquids that need to be diluted with water prior to use, some are powders that are mixed with water, and while others powders should be applied dry. Insecticides in the last group are generally called dust insecticides. The first widely used insecticide was a dust called "insect powder", made from the ground leaves of the chrysanthemum flower.

Natural dust insecticides are made from minerals such as borate and silica, or from plants (see below). In addition to the dust insecticides made from minerals and plants there are also synthetic (man-made) conventional insecticides that are manufactured as dusts. Therefore the term "dust insecticide" does not necessarily imply natural/organic.

chrysanthemum flowers

Certain types of chrysanthemum flowers are the source of natural "Insect Powders" (pyrethrins). Original photo by USDA.

Silica dust & diatomaceous earth (DE) insecticides

Silica is often combined with the natural insecticide pyrethrum and a synthetic compound called piperonyl butoxide (PBO), but it can also be used alone. Natural silica comes from two sources. Amorphous silica which is manufactured by heating ordinary sand to a high temperature and diatomaceous earth which comes from the skeletons of tiny marine organisms called diatoms.

Silica is a desiccant that destroys the waxy covering that protects insects from excessive water loss so exposure to silica causes them to loose too much water and die. Pyrethrum and PBO are added to increase insect movement by stimulating their nervous systems. This brings the insects into contact with the silica dust more readily. Silica dust itself must be kept dry to be effective so is often used only indoors or in gardens during dry periods.

Silica dusts are especially useful as crack and crevice treatments for bed bugs, in food handling areas for cockroaches, carpet beetles and nuisance ants, and as wall void treatments for carpenter ants. While diatomaceous earth is sometimes suggested as a carpet treatment for fleas there are much better materials now available for flea control. The most common silica-based products used for pest control are the products "Drione" and "Tri-Die". A variety of silica-based insecticides can be purchased here, our affiliate. Be sure to check product labels for permitted uses.

Boric acid & borate dust

Borates are the sodium salts of boric acid (sodium borate). Borates are minerals and have a wide variety of industrial uses as additives, wood preservatives, insecticides, plant nutrients, and detergents. Borates act mainly as "stomach poisons" when formulated in baits for ant and cockroach control or used as dry powders or liquids on surfaces. Borate dust remains active as long as it stays dry and undisturbed. The product Timbor, for example, is very effective for powderpost beetles and dry rot fungi as a surface spray and for carpenter ants as a wall void dust treatment. Borate powder also is used to treat carpets for fleas. However, as with diatomaceous earth, there are better materials now available for flea control (see Boric Acid & Borate Insecticides). A variety of borate-based insecticides can be purchased here, our affiliate. Be sure to check product labels for permitted uses.

Botanical, plant-based dusts

Botanical dusts are both the oldest and the newest natural dust insecticides. Dusts made from the ground, dried flowers of the chrysanthemum plant, containing the natural insecticide pyrethrum, are among the oldest commonly-used insecticides. On the other hand, some of the newest botanical (plant-based) dusts contain natural plant oils in combination with some kind of dry carrier such as silica (see Using Botanical Dust Insecticides for much more information about dust insecticides in general as well as how they are used). A variety of botanical dust insecticides can be purchased here, our affiliate. Be sure to check product labels for permitted uses.

Related Articles

Using Diatomaceous Earth Insecticide

Using Pyrethrum Insecticides

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