QUESTION:

I have noticed in the last three months that on three occasions, I have run across people who use diatomaceous Earth in an attempt to control bed bugs. It is usually piled up on furniture, floors, beds, etc., and in one incident the dust was even thrown all over a box of boxes. I tell the customer to clean up the dust because it is a desiccant that will harm them. You can walk into the room and see the dust billowing in the air. I cannot see any advantage to what they are doing except in their own minds.

ANSWER:

Diatomaceous Earth is actually a very effective dust for bed bugs, according to a study done by Dr. Mike Potter and others in 2009, where they compared various dust active ingredients on bed bugs. A very short summary of their results is that they found Tempo Dust to be the superior product (in their study), killing 100% of the exposed bugs within 24 hours, including resistant strains from New York and Ohio. Second was Drione Dust with 100% kill within 72 hours, and then DeltaDust and MotherEarth Dust with 100% kill taking 7 to 10 days. The dust that would NOT have any effect on bed bugs is boric acid, since this active ingredient needs to be ingested to have an effect, and bed bugs would be incapable of ingesting dusts.

The problem is that homeowners can buy anything and everything on the internet, and then use it without any knowledge of how it should be used, and this is what leads to most problems with pesticides. In your situations these people are horribly over-using the dust, and even though DE is relatively harmless to humans when used properly, once applied in this manner where they could be inhaling it there may be health concerns. It should not be inhaled, and excessive amounts on the skin could cause irritation to the skin with its drying effect. However, I would bet dollars to donuts that the websites they purchased this material from touted the dust as "nontoxic" and "safe" and "harmless", giving the people the impression that no matter how they used it there could be no harm to them.

A dust becomes physically repellent to insects when the amount is so heavy that the bug is trying to wade through it. What this accomplishes may be nothing more than forcing the insect to find another path around the dust to get where it needs to go. An extremely light layer of dust is all that is needed, and once the bug gets a small amount of the dust onto its exoskeleton the work of the dust begins. The difference between DE and Drione is the mechanism of action, according to Mike Potter et. al. The silica aerogel dusts (Drione, Tri-Die) are both abrasive and sorptive, so they not only cut through the waxy layer of the exoskeleton, but also tend to absorb moisture from the bug, accelerating the process of dehydration of the bug. Diatomaceous Earth (MotherEarth D, Alpine D) are abrasive only, so they ultimately cause the same effect of dehydrating the bug, but take longer to do it. The pyrethrum in the Drione and Tri-Die probably help with knockdown as well.

So, nothing wrong with the use of DE for bed bug control, but you should attempt to help these customers to do it correctly, which they may not be equipped to do. Dusts should ONLY be used within closed voids where they will not get all over surfaces that people and pets then will contact. If they tell you that it's okay, because the stuff is not toxic, be armed with some literature from universities that explains the possible health consequences of breathing too much of the desiccant materials. They should remove all of this dust, but to do so they should use a high efficiency vacuum that will remove the fine particles of the dust. Provide them with literature that explains that a single product or technique is not going to eliminate bed bugs, but that a multi-pronged approach is necessary. Prevention of bed bugs, which they could be attempting, is better done with traps and monitors designed to capture bed bugs, and if they do continue to use the dusts they should be applied into wall voids and crevices.