Diatomaceous Earth (DE) is a geological deposit made up of fossilized skeletons 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 breakup into tiny pieces of glass so tiny that the material feels like powder.  The diatom shells are covered in sharp spines that make them dangerous to exoskeleton insects, but not to animals with internal skeletons.  The pines of the diatom skeletons pierce the soft waxy body tissues of the insects between their hard exoskeleton plates and it is through these numerous microscopic wounds that the insect loses bodily moisture to the point of dehydration, and then it will dry up and die.  Creatures with internal skeletons such as humans, cattle, birds and pets have means of resisting such damage and are not harmed.  Diatomaceous Earth works in purely physical and not chemical manner and thus has no chemical toxicity.

It is possible to mix a small amount of DE into a stored grains and beans to deter insect infestations without having to remove the dust again before consuming the grains.  In several tests, DE gave better protection of grains than Malathion, particularly over the long term without exposing anyone to the danger of toxic chemicals.

To use it in food storage, you should mix thoroughly one cup of DE to every (40) forty pounds of grains such as barley, buckwheat, corn, wheat, oats, rise, and a mixture of these grains.  This works out to approximately one cup of DE to every (5) five gallon bucket full of grains.  You need to make certain that every kernel is coated so it is better to do the mixing in small batches where you can insure more even coating.  Both the grain and the DE should be dry when doing the mixing otherwise you will get very uneven distribution.  When used at proper rates, DE has been effective against ants, aphids, bollworm, caterpillar, cockroach, corn worm, earwig, house fly, fruit fly, lead perforator, leaf hopper, lygus bug, mite, weevil, red spider mites, slugs, snail, termites, Japanese beetle (grub stage) and many other insects.

There is no residual danger of contamination.  In fact, DE is actually beneficial to the soil.  It is loaded with trace minerals.  However, there are a few precautions.  DE is very dusty and can cause lung irritation if breathed heavily, so when applying it dry always wear a good dust mask or stand up wind.  The second precaution is that natural DE will kill beneficial insects too, so use it sparingly to kill problem infestations of harmful insects.

There are actually two kinds of Diatomaceous Earth to be found on the market and only one of them is suitable for use as insecticide to use in stored grains.  The kind that is NOT for food is the type sold by swimming pools suppliers as filtering agent.  DE to be used for filtering has been subjected to a heat treatment that dramatically increases its crystalline silicate content and makes it unsuitable for storing grains.  The DE that is needed for use in grain storage has not been heated and has a crystalline silica content of no more than 1 to 1.5%.  It is commonly sold in hardware and garden stores of feed stores as an “organic pesticide.” 

Diatomaceous Earth can be used effectively in houses to prevent the entry of certain insects such as earwigs, ants, silverfish, spiders, 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.  It is important to place a small amount of the DE powder in corners, cracks, crevices, and other areas where insects might hide. 

Another use is in animals and birds for control of external parasites, mites, fleas, and flies.  This is achieved by dusting the animals or birds and the litter or bedding areas, nest boxes and perches.  It has also been included in the diet (two percent in the grain ration) to control certain internal parasites and this practice is aid to result in lower fly population in the resulting manure.  In fact DE has been used for worming animals, controlling fly larvae in manure, as a trace mineral mixture, and insecticide, a treatment for stored grains and a soil conditioner.

In closing, whereas with a contact pesticide, the insect dies quite quickly, with DE control may take several days (6 to 72 hours to kill).  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 is that if large area is being treated with a powder duster, the applicator should wear a protective mask to prevent inhalation.  Diatomaceous Earth is a natural grade diatomite; however, the continual breathing of any dust should always be avoided.