DIATOMACEOUS EARTH: A Non Toxic Pesticide

MACDONALD J. 47( 2): 14, 42 (May, 1986)

by Professor Stuart B. Hill

Department of Entomology and Ecological Agriculture Projects

"...........Probably the most effective naturally occurring protective powder is diatomaceous earth. This is a geological deposit made up of the fossilized skeletons and tests of siliceous marine and fresh water organisms, particularly diatoms and other algae. These skeletons are made of hydrated amorphous silica or opal. When crushed, they break up into tiny pieces of glass'' (so tiny that the material feels like talcum powder). This is easily picked up by the hairy bodies of most Insects. whereupon it scratches through their protective wax layers; and they also absorb some of this material. the result being that the insects lose water rapidly . dry up and die Further protection is provided by the powder's property of repelling many insects. A similar principle probably accounts for the fact that birds frequently take dust baths, presumably to rid themselves of parasites.

Although patents for diatomaceous earth formulations were issued in the United States in the late 1800s it was not until the 1950s that the first commercial formulations of it became widely available, and between 1963 and 1970 a series of studies on DE were conducted by the U.S. Department of Agriculture.

In several tests, DE gave better protection of grain than malathion, particularly over the long term, without exposing anyone to the dangers of toxic chemicals...............

In houses it can be used effectively to prevent the entry of certain insects such as earwigs, ants, and cockroaches, and to control these and others that are present in cupboards containing food, carpets, basements, attics, window ledges, pet areas (for fleas), etc. In all of these examples it is important to place a small amount of the powder in corners, cracks, crevices. and other areas where insects might hide. Whereas with a contact pesticide the insect dies quite quickly, with DE control may take several days. The more important difference is that the effect of the protection provided by the chemical is short-lived. whereas DE will control the pests as long as the powder remains. In this respect DE is an ideal pesticide; it is residual but nontoxic. The only health precautions that need to be taken are that if large areas are being treated with a power duster, the applicator should wear a mask to prevent inhalation................

Another use is in animal production units for the control of external parasites and flies. This is achieved by dusting the animals and the litter or bedding area. It has also been included in the diet (two per cent in the grain ration) to control certain internal parasites, and this practice is said to result in lower fly populations in the resulting manure........."

About DE | Garrett DE Article | Hill DE Article | Purchase | Site Map | Certificate of Analysis