Richard Fagerlund I mentioned diatomaceous earth in a recent column and, since then, I have been inundated with questions about its safety, how to use it, how it works and where to get it. I want to devote this column to this product, which — when it is used properly — may be the most effective and safest pest-management tool available.
Diatomaceous earth is nontoxic to mammals and birds. However, there are several types of DE. Use only food-grade DE in and around your home or business. It is labeled GRAS or Generally Regarded As Safe, and kills insects more effectively. Do
not use swimming-pool grade as this form is not effective as an insecticide. It also may contain a high level of crystalline silica which, when inhaled, can cause silicosis, a deadly lung disease.
Food grade DE is sold as "fossil shell flour," and is approved by the FDA to be added to livestock rations at a rate not to exceed 2 percent. As a livestock feed additive at 1 percent to 2 percent, it can kill worms and other internal parasites. I spread it around the barn to control flies and it works very well.
To control fleas, lice and ticks, it can be rubbed into your pet's fur from the neck down, paying particular attention to the tail area. Be sure to keep it away from your pet's and your own face and mouth. All forms of diatomaceous earth are abrasive to the lungs and eyes, so it's important to use proper personal protection when using this product. If you are working in an enclosed area, such as an attic or crawl space, you should wear a dust mask and goggles.
Diatomaceous earth is mined from the fossilized silica shell remains of unicellular or colonial algae or one-celled pytoplankton in the class Bacillariophyceae, better known as diatoms, that converted the silica they ingested to form their shells. (Diatoms are animals that are related to the crustaceans of today.)
Diatomaceous earth absorbs the waxy layer on the surface of insect skins, causing the insect to desiccate, or dry out. The effective insecticidal form absorbs up to four times its weight in moisture, so it takes the oils from insects' skin, causing dehydration and death. In addition to its desiccant action, it works abrasively to rupture insect cuticles, allowing cell sap to leak out. It also can be used to control slugs and snails.
Food-grade DE has other uses, including cleaning and polishing metal and soaking up spilled oil and grease. It does not break down or leave harmful residues. Food-grade DE also controls mildew and brown rot. This least-toxic insecticide is considered harmless to humans and is used in stored grains.
But it's important to realize that while DE may be harmless if ingested, it still must be kept out of the eyes and we should not inhale much of it.
Diatomaceous earth also can be used to remove odors — it simply "grabs them."
To control insects, mix 1/4 cup food-grade DE in a gallon of vinegar and spray pests with the mix, or pour it into individual ant colonies as a drench.
You can make a very good pest barrier by applying petroleum jelly to an area — the trunks of trees, for example — and then lightly dusting the adhesive with food-grade DE.
I also use DE to control bed bugs, as it is safe and very effective.
When using diatomaceous earth, remember that less truly is more; try putting a pinch on a piece of paper and then blowing this tiny amount toward the infested area, or simply dust cracks, crevices and/or voids lightly with the powder.
You can put it in woodpiles, under stones and other hiding areas in your yard to control centipedes, scorpions, cockroaches and any other pests. If you want to put a barrier around your house, you can mix it with water — 1 cup per gallon of water — and spray it around the foundation. It will leave a whitish color where it is applied. It won't hurt insects when it is wet, but when the water evaporates, the DE remaining will be effective for a very long time.
It is possible to use DE to prevent termites in some situations. However, because it isn't a registered termiticide, a professional can't legally use it to eliminate termites — but you can put it in a crawl space to prevent termites from entering the structure. A crawl space would have to be totally accessible in order to treat it properly.
Some people also use food grade DE for garden pest control. You can dust your plants with DE to control aphids, thrips and many other plants. Make sure you mist the plants first so the DE adheres to the leaves. Unfortunately, DE will also kill any beneficial insects — especially Hymenoptera parasitoids — on the plants, so you have to be careful.
You can find diatomaceous earth in some health-food stores. Moses Health Food in the North Valley of Albuquerque carries it. You can also order it online. One New Mexico supplier is www.pestcontrolsupplies.com.
Contact Richard Fagerlund at firstname.lastname@example.org or call him at 505-385-2820.