Check the label before you dust the house for bugs

You have a bug problem and you have read that a cheap natural powder will fix it. The powder is diatomaceous earth, ground from the fossilised shells of tiny water organisms, and some people use it against fleas, ants and bed bugs. It can help. It also comes in kinds that do not belong in a house, and the dust is not harmless to breathe.

Before you spread a drying powder for bugs, use only a product whose label says it is for insect control, keep the dust out of the air, and treat it as one part of the job rather than the whole fix.

This page is for someone about to put the powder down in a home. If you already have bed bugs in your bed, read the bed bug section first. If someone has already breathed in a lot of the dust, the box above is what you need.

How it works, and why natural does not mean harmless

Some people explain that the earth works by drying the bug out: it takes the oils from the bug’s outer shell, rather than poisoning it. NPIC says the same, and adds that it keeps working only while it stays dry and undisturbed.

That is why one person points out that non-toxic can mislead: a dust can hurt a body physically without being a poison. Some people also warn that it harms anything with a hard outer shell, including ladybugs and wasps, not only the pest.

Which kind: what people say and what the EPA says

Some people say to use only food-grade earth indoors, and that the kind sold for pool filters is much more dangerous and less use against bugs. Some people give the reason as crystalline silica, a form of the mineral that scars the lungs after long exposure. Some people warn that cheap industrial earth is extremely dangerous, and one person points out that a pool shop’s earth is not the same product as the food-grade kind.

There is a catch in the advice to use food-grade. NPIC describes food-grade earth as a purified product, used in animal feed and to clear wine and beer; that is a description of the grade, not a claim that it is made for pests. For bed bugs, the EPA says pool or food grade earth should not be used, and that the product to buy is one registered by the EPA as a pesticide, which uses a different size of the tiny shells and so lowers the hazard when breathed. NPIC says over 150 earth products are registered for use inside and outside buildings, and that reading and following the label is how to limit exposure.

So on food-grade, what some people say and what the EPA says part ways, and this page follows the EPA: take a product whose label says it is for insect control. If the label does not say what the product is for, or says it is for pools, filters or food, put it back. This page checked US sources only; the UK rules for pest-control products were not checked.

Keep it out of the air

Some people warn that breathing the dust can scar the lungs, and some say the risk is higher for people with asthma, older people, children and smokers. One person says handling a large amount left their throat and lungs scratchy for a couple of days. NPIC says the dust can irritate the nose and nasal passages, and that an extremely large amount breathed in can bring coughing and shortness of breath. It also says the dust can irritate the eyes and dry or irritate the skin.

One person argues that the lung-scarring warnings belong to the processed kind and to long, heavy exposure at work. Even if that is right, NPIC lists breathing it in as a way it can irritate, so keep it out of the air either way.

Some people suggest a bulb or bellows duster and a ventilated room, so the powder goes on in a thin line rather than a cloud. One person says to use it sparingly and keep it off your clothes. One person says not to put it thickly in carpets, because it is hard to remove and raises dust; another says it clumps when wet; another says it can clog vacuum filters. One person says to wear a respirator; this page did not check which kind, so follow the label.

Thickness matters for the bugs too. One person says pests will walk around a thick layer, and another that they begin to avoid treated areas over time.

If it is bed bugs

Some people say the earth is an effective tool against bed bugs and fleas, though it may take time. One person says it failed completely on bed bugs over six weeks and the infestation got worse. Some people say it works best beside other methods, and one person says it cannot clear a moderate or severe infestation by itself and that you should get professional help. These views do not agree, and this page cannot settle it for your home.

The EPA says desiccant powders can be effective against bed bugs but may take several months to work. It also says that trying to kill bed bugs by turning up your thermostat, or with a propane space heater or fireplace, does not work and is dangerous, and that sealed mattress and box spring covers trap bed bugs so they die inside. A fogger should not be your only method, and improper use can harm your health or cause a fire or explosion (EPA).

Some people describe an infestation lasting months in a building where neighbours kept spreading it. This page does not cover what a landlord must do about it.

Ants and water

One person says ants avoid crossing the powder rather than dying from it, and the answer they were given was to use bait beside it. One person says most infestations depend on water, so fixing leaks and removing standing water matters.

Who this page is not for

If bed bugs are already in your bed, this page is not a treatment: the EPA steps above, and a professional for a hard case, are. If you were thinking of eating the earth, or giving it to a pet as a supplement, this page does not cover that; one person says never to eat it, and if a child or pet has eaten some, see the safety box. If your problem is mosquitoes, this page does not cover repellents. And if someone in your home has a lung condition, ask a professional before dusting indoors at all.