December 17, 2011 Diatomaceous Earth for Pest Control Originally published in the Contra Costa Times by Earlene Millier, UC Master Gardener

The oldest pesticide still works!

SUMMARY Q: I don’t want to use any kind of type of DE is processed differently and chemical pesticide in my house because of does not work for pest management. Diatomaceous earth (DE) my kids and pets. Someone said I could You will need to look for products is an effective pesticide use a product called diatomaceous earth. specifically made for pest control, which with very low toxicity to Is this effective on ants and cockroaches? are usually available in bags or cartons in mammals. It works by Where do I buy it & how do I use it? the pesticide aisle. It can be used both mechanical action, indoors and in the garden, but here we’ll abrading an insect’s A: Diatomaceous earth (DE), might be deal with indoor pests since that is what waxy protective coating, the world’s oldest form of pest control. you asked about. causing dessication & Dusts in general, and DE in particular, death. Always wear are effective against a wide variety of How DE Works: protective gear (dust crawling insect pests. Birds and other DE is effective on cockroaches, ants, mask, gloves, & goggles) animals have known this for eons; earwigs, silverfish, crickets, millipedes, and follow package hence, the popularity of dust baths to centipedes, bedbugs, and many other instruction when kill mites and other body irritating pests. crawling pests that sometimes invade applying. our homes. DE does not act as a poison About Diatomaceous Earth (DE): on pests: it works by abrading the waxy DE is usually found as a soft, gray, coating from the outer skeleton of the chalky rock and is mined from geological insect, which then dehydrates and dies. deposits made up of the fossilized shells If insects ingest DE, it is also lethal. DE of diatoms, single-celled aquatic has very low toxicity to mammals, organisms that are as much as 20 million including humans, but it can be an years old. The rock is processed into irritant so be sure to wear a mask, gloves dust for many uses, pest control being and goggles and follow the instructions only one. Around the home it is also on the product label. used in swimming pool filters, but that

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Effective Use of DE: directly where possible. If you have an In order to be effective, DE must be dry, ant invasion, dust the trail of ants with and it must be applied in a wide but thin DE. “Because DE kills layer. Pests will avoid DE if they can, so the best application makes it impossible Good for Long-Term Control: insects in a for them to avoid. Use a bulb duster, a Insects walk through the dust, and bits plastic condiment dispenser bottle, or a of it cling to them because of mechanical way, dry, empty plastic squeeze bottle. electrostatic attraction. Nesting insects, Appropriate applicators are usually sold like ants, will carry the DE back to the rather than by poison where DE is sold. Fill the container no nest where it will be spread around. DE more than half full, and then use a kills slowly and it might take a few days. action, it is unlikely to squeezing, “poofing” motion to dispense Because DE kills insects in a mechanical a thin layer of dust in areas where pests way, rather than by poison action, it is cause insects to build are found or may be hiding. Include unlikely to cause insects to build up such areas as cracks and crevices, behind resistance, and this makes it particularly up resistance, and this and beneath stoves, refrigerators, sinks, useful for long-term control. cabinets, garbage cans, window frames, makes it particularly attics, basements, and in wall voids. You For More Information: can squeeze the dust into wall voids by For more information about using DE, useful for long-term removing electrical outlet and switch see UC Pest Notes for specific pests: covers, dusting inside the wall, then http://ipm.ucanr.edu/PMG/menu.house.ht replacing the covers. Try for a light control.” ml coating, widely spread. Hit insects

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