As I dealt with the cockroach infestation in my New York City apartment, I discovered a tremendously powerful all-natural substance called Diatomaceous Earth. It is a naturally occurring substance made up of the fossilized remains of tiny hard-shelled phytoplankton called diatoms. This non-toxic powder has the ability to kill roaches (and a whole bunch of other things) without poison. It is a microscopically abrasive powder that cuts and scratches the roaches inside and out. Since it is not a poison, it doesn't lose potency over time. So, one good application will last a long while.
Because I had a baby in the house when I was looking for solutions, I wanted an option that was non-toxic to humans for long-term use. Diatomaceous Earth seemed like an ideal product, so I started to hunt around for a local supplier.
In New York City, Diatomaceous Earth wasn't readily available (I didn't have time to search around at gardening centers) so I ended up ordering it online from Amazon. They also had a mint oil based non-toxic roach spray, so I got a couple cans of that as well.
When my 4 pound bag of Diatomaceous Earth arrived from Amazon, I immediately set out to use it. I discovered a few things about how to most effectively use Diatomaceous Earth for wiping out a cockroach infestation.
The two common forms of Diatomaceous Earth you will come across are 'food grade' and 'pool filter'. Always purchase 'food grade' Diatomaceous Earth for pest control. The Diatomaceous Earth sold for use in swimming pool filters has been heat processed. This processing changes the physical structure of the product and makes it completely ineffective for pest control. Other chemicals may also be added during the processing.
'Food grade' Diatomaceous Earth will be safe to use around your home and will not contain dangerous additives.
There are Diatomaceous Earth formulations sold which are specifically labeled for pest control. These may or may not have any other chemical additives. So, read the label carefully. Often, the manufacturer will add some form of bait or attract-ant to the mix to entice the cockroaches to interact with the powder and ingest it.
The first important thing I noticed from using the Diatomaceous Earth is that, while it may not be poisonous to humans, it IS an irritant. It will get on your skin and dry it out like one of those facial mud-packs (they feel like every drop of moisture has been sucked out of your skin.) Diatomaceous Earth also has a very mild, but noticeable, odor and can irritate your eyes.
The second important thing to note is that Diatomaceous Earth will easily disperse in the air and form a cloud of fine particles that hang there a long time and then eventually settle on everything in the room. This is not necessarily a bad thing because it also helps you to get it in the places where the cockroaches live.
Based on this first experience, I recommend wearing a dust mask, eye-goggles, gloves, and long sleeves and pants while applying this product. Also, go slow when applying to prevent over-application.
The goal with a product like Diatomaceous Earth is to get the roaches to track it back into the walls where it kills other roaches in the nest. A common application is to dust it under sink cabinets, stoves, refrigerators, and along baseboards. It is also good to spread it around outside if the roaches are coming from there (in an outdoor application the powder needs to be re-applied after rain.) I wanted to be even more aggressive.
If individual roaches tracking the Diatomaceous Earth into the walls was a good thing, I reasoned that coating the interiors of the wall with the powder would be even better - like a giant cockroach minefield in the wall. I decided to drill small holes in the space between the wall studs in my kitchen and bathroom and blow the Diatomaceous Earth inside to coat the interior surfaces.
WARNING: If you decide to copy my extreme approach - you do so at your own risk. Walls contain plumbing pipes, electrical wiring, and other hazards. Repairing the holes you make requires skills you may not possess and the results may be unsightly.
A little drywall patching and paint was required afterward (fortunately I am experienced with home remodeling.) In the end, this extreme application let me finally relax in my own home instead of constantly scanning for roaches. It was worth the extra effort for me.
Diatomaceous Earth is applied by 'dusting' it onto surfaces.
Once my bottle was filled with Diatomaceous Earth, I set out to dust under the refrigerator, stove, and along the baseboards in the kitchen. I tipped the bottle and squeezed it quickly to 'puff out' a little powder.
I was concerned early on that the Diatomaceous Earth would clog up the bottle, but the fine light powder dispersed nicely. However, I got a little aggressive trying to blow the powder back under the fridge and, when I took a break and looked up, I noticed a cloud of dust hovering in the kitchen. Go easy.
IMPORTANT NOTE: Wear a dust mask when applying Diatomaceous Earth.
When it came to my goal of coating the inside of my walls with Diatomaceous Earth, blowing the dust in the walls turned out to be a much easier task than I had anticipated. Only a small hole was needed to get the Diatomaceous Earth inside and some vigorous work with the bottle created a cloud of dust inside the walls which coated every surface with roach killing powder – sweet!
One nice thing is that the dust clings easily to many surfaces. So, the sides of the stove and lower cabinets became roach death traps. In fact, the vast majority of the kitchen surfaces became inhospitable to roaches.
I was pleased to discover that on the day following my first application, the number of roaches spotted in the kitchen had declined noticeably. The few that I did see moving around were going slowly with a coating of the Diatomaceous Earth on their bodies. They looked like sugar-frosted roaches. I found a few more in glue traps placed around the kitchen that were also coated in dust.
Unfortunately, a new horror kicked in when I realized the roaches were moving into the living room looking for new hunting grounds. I placed several glue traps along the walls in the hallway to capture the explorers before they could reach new rooms.
The second day after applying the Diatomaceous Earth, we had almost no roaches in the kitchen at all. I did the usually rattling of dishes and opening of cabinets designed to flush the roaches out of hiding and found nothing. This was all the more shocking given the fact that I had fallen asleep with dirty dishes in the sink and before taking out the trash.
While washing the dishes, one lonely baby roach came out of hiding and I quickly dispatched him with a shot of my mint oil spray!
I was extremely pleased with the long-lasting results I got from Diatomaceous Earth. About one year later I renovated the kitchen in the apartment. This involved ripping out all the cabinets and opening up a large portion of the walls. I sealed the gaps around the hanging cabinets so well that I found a large group of Diatomaceous Earth covered dead cockroaches that were trapped behind them.
The insides of the walls had a thin layer of Diatomaceous Earth dust on them with a small pile of powder at the bottom where any cracks a cockroach could crawl through might be located.
What I didn't find in the walls when I opened them up was any cockroach activity. I did not see one roach moving around the treated walls during the entire renovation. The same woman was still living upstairs and her apartment was as cockroach-ridden as ever.
I eventually moved away from New York, but still keep a bag of Diatomaceous Earth on hand for pest control.