Written by A O’Neill – Licensed Pest Control Technician
Diatomaceous earth is often portrayed as the Holy Grail in the DIY fight against bed bugs on so many websites because it’s non-toxic and eco-friendly.
While it does kill bed bugs, it’s important to know just how effective it really is in eliminating these pests and if it’s worth using, or if there is a better option.
What Is Diatomaceous Earth?
Diatomaceous earth (often referred to as DE and Bed Bug Killer Powder) is an off-white silicon dioxide-rich fine powder made from fossilized aquatic organisms called diatoms.
Diatomaceous earth acts as a desiccant, and desiccant dusts are used for their residual effectiveness alongside other treatment methods, such as heat, by pest management professionals (PMPs).
Only use food grade DE for pest control. Never use pool grade DE around your home as it is heat-treated to convert the silicon dioxide to crystalline silica, which can cause respiratory problems such as a progressive lung disease called silicosis.
How Do Diatomaceous Earth and Desiccants Work?
DE works like extra-fine sandpaper that wears away the bed bug shell’s waxy protective layer which prevents moisture loss.
As the bed bugs crawl through or over the DE’s abrasive particles, the waxy layer becomes damaged and moisture is then lost from the bed bug’s body so it slowly dehydrates and dies.
The EPA recommends using desiccants as part of controlling an infestation, and the good thing about DE and other desiccants is bed bugs are not resistant to them as they are to certain pesticides. The other good thing is that they are long-lasting so stay effective if undisturbed.
Another type of desiccant is silica gel which is synthetically manufactured, usually from sand. A popular silica gel used to kill bed bugs is CimeXa insecticide dust, which also contains silicon dioxide as the main ingredient.
However, silica gel is not actually a gel at all, it is manufactured from silica into a lightweight white fluffy powder.
You’ve probably come into contact with silica lots of times when you find those small packets of silica gel in packages. These are used as they absorb any moisture and keep the product dry.
Silica gels work in a slightly different way to DE and do not abrade the wax covering. Instead, when the ‘gel’ comes into contact with the bed bug it acts more like a sponge absorbing the wax from the outer shell and sucking out the moisture causing dehydration and death.
The downside of both DE and silica gel is that neither of them kills bed bug eggs. They are only effective on crawling bed bugs as both products need to contact the waxy coating of the shell to work.
Which Is Better For Eliminating Bed Bugs? DE Or Silica Gel?
Both have their advantages if you want to kill bed bugs naturally. Diatomaceous earth and silica gel are both non-toxic, safe to use, eco-friendly, and long-lasting.
In laboratory studies, DE was found to have a high success rate in killing bed bugs. But would the same success rate be obtained in a real infestation usually found in homes?
Researchers at the University of Kentucky and pest professionals put this to the test. They treated 6 bed bug-infested apartments with only diatomaceous earth (MotherEarth D).
The results were disappointing and showed the bed bugs were still active in all but one of the apartments after several weeks.
One of the reasons put forward as to why the bed bugs survived desiccation is because they are able to withstand extreme dehydration (they can survive a year without a blood meal) as they lose moisture at a very slow rate.
After the disappointing results with DE, the researchers conducted another study both in the lab and in bed bug-infested apartments involving another desiccant dust, silica gel.
The results from the lab study showed all bed bugs had died within 24-48 hours of being exposed to a barely visible amount of CimeXa dust.
CimeXa dust was then tested in the field. Ten bed bug-infested apartments were chosen, six were treated with CimeXa dust and four treated with CimeXa mixed with water and applied as a spray.
The results were impressive using CimeXa dust which resulted in an 82.3% reduction in bed bugs in the first week and 98.1% fewer bed bugs were found by the end of the trial.
The results from CimeXa mixed with water as a spray application were not so good. The average reduction in bed bugs at the end of the trial was only 33.9%.
How Long Does It Take For DE and Silica Gel To Kill Bed Bugs?
When both were tested in a lab using carpet samples dusted with both products, the results showed over a 24 hour period that silica gel was effectively far superior with 97% of bed bugs dying compared to diatomaceous earth only killing 10%.
Is Silica Gel More Effective In Treating Bed Bugs?
As a PMP I use desiccant dust as part of bed bug treatments. Although DE will kill bed bugs, it’s just too slow, and when you have a growing bed bug problem you want it gone as quickly as possible.
Silica gels are the obvious choice but one important point to note is that if you are going to use silica dust or DE, it should not be used as a stand-alone treatment.
Bed bugs are hard to get rid of, so use together with other methods of treatment recommended in our guide, including:
- mattress encasements
Read our detailed guide on how to kill bed bugs for the exact steps to take.
Bed bugs are so small they can hide out of the way literally anywhere. They are found in the tiniest of cracks and crevices and these are the areas that you want to pay attention to when using desiccant dust.
Silica gel, such as CimeXa, is best applied as a dust treatment and should be applied after the room has been heat treated.
Silica gel has a very lightweight texture so a polyester angled paintbrush is recommended for most crevices and surfaces, and cosmetic or artist brushes are ideal for applying the dust along seams, tufts, and into creases on mattresses and other furniture.
A hand duster or puffer bottle can be used if you prefer for behind baseboards, in plumbing voids, cracks, and crevices, and in other difficult to reach areas, but not on furniture and flat surfaces as it becomes airborne and drifts onto other surfaces you do not want to cover.
Always wear gloves and a mask when applying any dust.
Before you begin clear any clutter away and vacuum the room. See our guide on how this should be done.
Apply where the bed bugs will most likely come into contact with the dust, such as:
- Along baseboards and in any cracks
- Behind wall hangings – pictures, paintings
- Behind switchplate coverings but not directly in electrical boxes
- Carpet track strips
- Mattresses and box springs before encasing them, bed frames, and headboard
- Underneath furniture and in any folds
- Plumbing voids
- Harborage areas (where they congregate when not feeding)
You can also work the silica powder into the bedroom carpet with a brush in the infested and adjacent areas.
Silica Gel As A Preventative Measure
It’s also a good idea to apply silica gel around the perimeter of the infested room close to the baseboards. This helps prevent the infestation from spreading to other rooms and from reinfesting your (bed)room if bed bugs are entering from behind the baseboards from another room or apartment.
One important point to note is that it’s important to read the application instructions and stick to the usage rate. The dust should be applied as light as possible, if the coating is too thick, the bed bugs will avoid walking through it and won’t pick up the dust.
Desiccant dust does not break down so remains active for years if left undisturbed. However, it will need reapplying along the baseboards, for example, if the floor has been vacuumed along them removing the dust.
REMEMBER – The bed bugs have to come in direct contact with the desiccant dust for it to work and kill them.
While diatomaceous earth is effective in killing most insects, it’s not the best option when you want to be free from bed bugs as soon as possible. A silica gel is a better option and will kill a greater number of bed bugs than DE, and within a shorter time period, when used together with other treatment methods.