Diatomaceous Earth And Boric Acid: What Dusts Really Do

Yes, dusts kill insects. No, a bag of powder is not a treatment. Diatomaceous earth, silica gel and boric acid dry an insect out or poison it slowly, so they only work while they stay dry, only where the insect actually walks, and only over days to months rather than overnight.

What A Dust Does To An Insect

It takes away the insect's ability to hold water. The U.S. Environmental Protection Agency's page on pesticides for bed bugs describes desiccants plainly: they destroy the waxy, protective outer coating on the insect, which then slowly dehydrates and dies. It names diatomaceous earth and boric acid as the two examples. The National Pesticide Information Center describes what is in the bag: diatomaceous earth is made from the fossilized remains of tiny aquatic organisms called diatoms, its main component is amorphous silicon dioxide, and it can contain very low levels of crystalline silicon dioxide.

Boric acid has a second route into the insect. The National Pesticide Information Center says boric acid can kill insects if they eat it, disrupting the stomach and possibly affecting the nervous system, and that it can also scratch and damage an insect's exterior. The University of California Statewide IPM Program explains how a cockroach eats something nobody fed it: the dust clings to its body as it walks through a treated area, and it swallows small amounts while grooming itself.

There is one genuine advantage here, and it is the reason dusts stay in a professional's kit. The EPA notes that because desiccants work through a physical mode of action, bed bugs cannot become resistant to them the way they can to pesticides with other modes of action. That is not a small thing in a state where store-bought roach spray has stopped working on German cockroaches.

Does Diatomaceous Earth Work On Bed Bugs?

It can, more slowly and less reliably than the bag suggests. Ohio State University's bed bug program lists dusts, diatomaceous earth and silica gel dust, along with mattress encasements, among the only over-the-counter products that are effective, and points them at places a liquid cannot go, such as electrical outlets. Ohio State University Extension's bed bug fact sheet (HYG-2105) calls both dusts promising and says they work by dehydrating the insect, then adds the part that gets skipped: the method is slow, control is best achieved by following an integrated pest management approach, and an infestation usually needs a licensed professional and often more than one treatment. EPA's do-it-yourself guidance puts a timeframe on slow. Desiccants may take several months to work.

Which dust, and which product, matters more than the pest on the front of the bag. A comparison of dust insecticides published in the Journal of Economic Entomology in 2016 found that only the silica gel dust caused 100 percent mortality from all three exposure methods, while diatomaceous earth products caused 65 percent or less in a brief exposure assay. A related study found label-rate doses of both products eventually reached 100 percent, but over very different timeframes: 3 to 4 days for the silica gel against 14 days for the diatomaceous earth product. A 2024 study in the journal Parasite went further down the shelf and found that diatomaceous earth bought at a supermarket and diatomaceous earth sold as a litter conditioner were ineffective, while a pest management grade product performed in the same range as Sommieres earth, 75 to 100 percent across its exposure tests.

Why The Bag From The Shelf Usually Fails

Almost never because the chemistry is wrong. The failures are about grade, placement, moisture and patience, in that order.

1. It is the wrong grade. The National Pesticide Information Center is direct about food grade products: they are not labeled for pest control and have not been evaluated for pest control related risks, their labels do not tell you how much to apply or what protective gear to use, and the dust may be finer, with a smaller diameter diatom that is more harmful if inhaled. The EPA says to use only desiccants registered by the agency and labeled for bed bug control.
2. It is in the wrong place. The University of California Statewide IPM Program puts boric acid powders and desiccant dusts in hollow walls, under refrigerators and other undisturbed hiding places. For bed bugs, the EPA limits desiccant use to cracks and crevices to reduce the inhalation risk. A visible line of powder along a baseboard is in neither category.
3. Nothing walks through it. The whole mechanism needs contact. Dust sitting somewhere the insect does not travel is housekeeping, not treatment.
4. It gets wet. The same IPM program says these materials are very effective as long as they remain dry and undisturbed, and the National Pesticide Information Center notes that the effectiveness of boric acid dusts is reduced when the dust gets wet. A damp Canton basement, a mopped kitchen floor and a crawlspace after a wet week all end the job early.
5. The clock runs out. Several months is longer than most households will keep at it, and far longer than a German cockroach population needs to grow past the point where a powder matters.
6. It does not change what feeds them. Ohio State University Extension's guide to choosing a pest management company makes the point about any treatment: sanitation and structural deficiencies listed in a report have to be corrected for pest management to work.

Is It Safe Around Kids, Pets And Food?

The risk here is the dust itself rather than the chemistry. The National Pesticide Information Center says that if it is breathed in, diatomaceous earth can irritate the nose and nasal passages, and that an extremely large amount inhaled can bring coughing and shortness of breath. On skin it causes irritation and dryness, and it can irritate eyes because it is abrasive. Most of it is amorphous silicon dioxide, but it can carry very low levels of crystalline silicon dioxide, which can build up in lung tissue, and the center notes that pest control use means spreading a more concentrated product inside a home, where breathing the dust is of greater concern.

The label is written around exactly that. The EPA's reregistration fact sheet for silicon dioxide and silica gel states that people may inhale particles when applying dust, aerosol and crack and crevice formulations, and that current product labels for dust formulations require the use of a dust mask. The center's technical fact sheet puts boric acid in EPA toxicity category III for most acute effects, and the same IPM guidance that recommends it keeps it inside walls and under appliances rather than out on a floor. By comparison, everything we apply on a State Shield Essential visit is pet-safe and kid-safe, and for most services you do not need to be home unless we need interior access.

When A Dust Is The Right Tool

When an inspection has already told you where the insects live, and that place is a void a liquid should not go into. That is how Ohio State's bed bug program frames dusts: one tool inside an integrated program, useful in outlets and wall spaces, not the program itself. Used that way, by someone who knows which product is labeled for the site, a dust is quietly good at its job.

Here is what it will not do on its own, and what the honest answer is instead:

• A German cockroach population in an apartment or a kitchen. It never was only your unit. That takes baiting, sanitation and access to the neighboring units, which is what cockroach control is built around.
• A bed bug infestation. Powder in a bedroom while the population spreads costs months. Bed bug inspections are free, and bed bug treatment uses heat that kills every life stage, typically in a single day. Our post on why store-bought bed bug products fail covers the rest of that aisle.
• Ants coming from a colony outdoors. Killing foragers in the kitchen leaves the nest intact, so ant control works the trail back instead.
• Termites. A colony is eliminated through baiting, not dusted. That is what the Sentricon system does.
• Mice and rats. No dust seals a gap. Rodent work is exclusion first, which is the whole basis of rodent control.

If you have already tried the powder and the insects are still there, you have learned something useful: you know where you saw them and what did not work. Bring both. Bed bug and termite inspections are free, roach and ant visits start with a free estimate, and you can schedule either one here or call 330-494-6199. We serve North Canton, Canton, Akron, Hartville and the rest of Stark and Summit counties, and we will tell you straight whether a dust is part of your answer or a distraction from it.