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Of Termites, Trenches, Toxins & Traps

Q. My wife and I want to plant fruit trees, grape vines and a vegetable garden. But our yard is currently grass that's been treated with chemicals for several years. Can we just remove the grass and plant? Or should we replace some of the soil? We want to place the vegetable garden near the foundation on one side of our home, but a friend warned that this might not be a good idea, as that soil was treated for termites before the house went in six years ago. Do you know how far this 'trench of death' extends from the foundation? We would like to plant as close to the house as possible.
    ---Carlos in Rockville, MD
A. The lawn part is easy. In a nutshell (with the full nut detailed in this Previous Question of the week on converting a lawn into a garden), you measure off sections for raised beds that are no wider than four feet, with two foot wide walking lanes between them. You remove the grass in the areas that will become the beds, lay down cardboard overtop of the existing soil, install frames that are about a foot high and fill them with a mixture of screened black topsoil and high-quality compost.

This eliminates the possibly contaminated soil—and prevents any remaining grassy areas from invading your growing space; a guaranteed problem in flat ground gardens. Raised beds also look much more attractive, require much less work and produce a much better harvest. Then just plant the fruits in open areas that get morning sun as described in our previous question of the week on fruit trees. It takes several years for new fruit trees and grape vines to produce their first edibles, and by then your past sins should be erased—if you get off the chemical treadmill and deal with your weeds safely and sanely with things like corn gluten meal and alternative, non-toxic herbicides of course!

For your trench of terror, we turned to noted 'common sense pest control' specialist Bill Quarles, Director of the BIRC—the Bio Integral Resource Center—in Berkeley, California, and editor of "The IPM Practitioner", whose latest issue features a lengthy comparison of chemically-filled trenches and bait stations for termite control.

It turns out that the trenches are just a poor idea in many ways. First, of course, you actually pay people to surround your home with a toxic moat. But the chemicals in that ditch of death peter out over time, and after five years or so, begin to fail at their task. So you spend a lot of money, endure a lot of potential exposure and the product stops working fairly soon.

Now, the fact that your moat of mayhem has probably lost a lot of its spark does not mean that you should plant there. Any planting right up against the house would INCREASE your risk of invasion by subterranean termites (the only type common in your Northeast/mid-Atlantic location). All they need to gain access to a home's foundation is for the soil to be constantly moist all the way to the wall; and a watered and mulched garden would create a superhighway for them.

"One of the best ways to prevent subterranean termite invasion is to simply leave an 18 inch wide space around the perimeter of your home clear of everything—plants, mulch, stones, etc.," explains Quarles. "These termites don't like to travel through dry areas, and anything growing or covering the surface of the soil will keep it moist and termite attractive."

Bill says that the typical trench of terror is a couple of feet deep, starts right up against the foundation and initially extends out about eight inches—with significant amounts of the chemicals migrating as far as three feet. So for safety and future termite avoidance (not to mention good airflow behind your plants), build your raised beds at least four feet or so away from the foundation—and, of course, don't mulch the area next to the house and do everything you can to keep it dry (which is also good for the house itself).

Options to a toxic trench abound. Bill points out that a sand barrier is very inexpensive to install as a home is being built, is highly effective against termite invasion and doesn't wear out. Another highly effective and totally non-toxic option is a stainless steel barrier, which should last about 25 years.

But the hands-down winner is outdoor bait stations; stake-like devices that are driven into the ground around the perimeter of a home. The tops flip up so inspectors can see if there's any activity or missing bait, while the below-ground bottoms allow termites to enter and take the bait, which is treated with the latest (and safest) termite colony killer. (Another advantage over trenches—the bait in these stations can be easily changed as more effective and safer termiticides become available; you're stuck with whatever they pumped into a trench.) The termites take the treated bait back to the nest, where it kills the Queen and ends the threat from that specific colony.

How well do they work? Bill explains that to be approved in Florida—where termite pressure is intense—outdoor bait stations have to clear infestations INSIDE an already infested home 90% of the time or better. You heard me—outdoor bait stations have to show that they will clear at least 90% of infested homes of their indoor termite problems.

How is this possible? It's simple, explains Bill—Termites live in big colonies outdoors and send workers inside structures to get food. The bait stations attract termites from the colony, they take the bait back to the nest, it kills the Queen, and with no new workers being produced, the indoor problem quickly ends. All without you spraying anything toxic inside OR outside. I don't know about you, but this is the best news I've heard all year!

---Special thanks to Bill Quarles and the BIRC for their excellent ongoing reporting on this very important topic. To learn everything you need to know to prevent and/or eliminate termite infestations in the least toxic manner, visit and order their special publication "IPM for Termites". They'll send you the issue of the IPM Practitioner referred to in this article as a free supplement! Go to, click on "Publications and Reprints" and follow the directions. The Termite package is listed under "Special publications".

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