Recently there was an article in a New Mexico paper about how a pest control company injects pesticides into the walls of homes to control all the pests that hide there. Someone asked me if this was something they should consider. The answer is, “No.”
First, there are very few pests that nest in our walls. Some ants will come in from the outside, and if they find ample food and water in the home, they may nest in a wall. This would include odorous house ants (Tapinoma sessile), little black ants (Monomorium minimum) and one or two other species. All you have to do is get the ants properly identified and then put out a bait they like. They will take it back into the wall and kill the queen and colony. Pesticides aren't necessary. What else nests in walls? German roaches in urban areas may nest in walls, but the American and Oriental roaches we have here in New Mexico prefer areas with access to water. A wall would be too dry for them to nest in. Centipedes, scorpions, spiders and other pests may get into a wall, but they won't stay there very long. The only real pest you will find in walls are subterranean termites, and the treatment method they use won't affect them. It may be possible to get a wasp nest in a wall, and if that is the case, this method may help. However it wouldn't be necessary to treat all the walls in the house.
Why else is this a bad idea? If there were bugs in the walls, they could get into your house. If the bugs could get into your house, so will the pesticides. Do you really want someone pumping pesticides in your walls that will come into your home and threaten the health of your family and pets? Nobody may get sick right away, but pesticides can build up in your body and those of your children and pets, and these toxins can compromise the health of all involved.
So why would anyone want to pump pesticides into your walls if there aren't any pests there? The answer is the same as why we sprayed baseboards in homes for many years. It’s perceived value. The industry sprayed baseboards to supposedly kill all the bugs that ran along the baseboard. Of course very few bugs actually ran along the baseboard. The real reason that baseboards were sprayed was to kill time in the customer's home to make it look like they were getting their money's worth. Most companies don't spray baseboards anymore, although a few still do. Power spraying the perimeter of a house was also widely used, but now is frowned upon as it has no real value, and they tend to kill more beneficial insects than pests. It is particularly silly when the pest company sprays around your home in the middle of winter.
If baseboard spraying, power spraying and pumping pesticides into walls isn't effective pest control, then what is? In reality pesticides should never be used in a home unless you have a pest infestation. In many cases, pesticides aren't even necessary then. If someone wants to spray your baseboards or pump pesticides into your walls, ask them to sign a paper stating that they will accept financial responsibility if anyone in your family or your pets get sick from the pesticides. If they agree to that (and they won't), then you can consider it.
The best thing you can do to control pests is to pest-proof your home. Some companies will help you do this. You can go to my website, askthebugman.com, and download my free book, which tells you how to pest-proof your house and how to control pests without toxic chemicals. Using pesticides when there are no pests present isn't good pest management. It is “spray and pray” (spray pesticides and pray you kill something). If you have any pest questions, or need a recommendation for pest companies that practice safe and effective pest control, contact me at firstname.lastname@example.org. I will also be glad to identify any pests you may have and make pest control suggestions. This is a free service, as is my book.