Natural Pest Control

November 5, 2009 By Doug Smeath

For anyone who has spent the winter months shivering and dreaming of balmier days ahead, spring’s arrival is good news. But the change in seasons brings new home and yard maintenance issues that must be dealt with. With careful planning, one of those issues—pest control—can be addressed in a healthy, environmentally responsible, green way.

Depending on where you live, any number of pests—especially insects or rodents—can cause health and safety issues and threaten the integrity and comfort of your home. Whether it’s termites, ants, rats, or something else, chances are they want into your house. And you want to keep them out.

For many homeowners with pest infestations, the first instinct is a toxic one: There is no shortage of poisons and baits on the market that promise to rid you of unwanted houseguests. But most of those toxic chemicals are not only bad for the pests; they’re harmful to you and your family, too. Additionally, toxins from pesticides and baits can leach into soils and contaminate water or disrupt local ecosystems. Pests play a role in the food chain and are vital to keeping other wildlife in your neighborhood healthy and thriving. Your pest-control goal should be keeping vermin out of your house, not doing away with them completely.

Nontoxic Strategies

There are a number of ways you can keep pests out of your home without endangering occupants’ health or the environment. Some of these strategies need to be implemented while the house is being designed and built; others can be put into place during routine maintenance. The initial costs of some nontoxic pest-prevention strategies can be higher than chemical controls, but those costs are frequently offset by the long-term effectiveness and durability of the structures, not to mention the reduced health-care costs that result from living in a healthier home.

Your pest-control strategy will depend on where you live. For example, some termite-specific prevention efforts are only necessary in areas at moderate or high risk for termites. In the United States, the risk of termites generally increases the farther south you live. The American Southeast and most of California are at especially high risk of termites. Meanwhile, a swath running from the Southwest through the Midwest to the Mid-Atlantic region and into New England—as far north as Massachusetts—bears at least a moderate risk of termite problems. The risk is fairly minimal in the Pacific Northwest, northern Midwestern states like the Dakotas and the Great Lakes states, and the upper Northeast.

Building and Design Considerations

  • Include no wood-to-concrete connections or separate any exterior wood-to-concrete connections—such as posts, deck supports and stair stringers—with metal or plastic fasteners or dividers.
  • Use solid concrete foundation walls or concrete-filled block. Foundations are particularly vulnerable to many subterranean pests, include termites.
  • Keep all wood, such as siding and trim, at least 12 inches above soil, as opposed to the 8 inches typically required by building code.
  • Use a sealed-to-the-wall vapor barrier for homes with crawlspaces on the floor or beneath a concrete slab to limit moisture intrusion and a damp environment that will appeal to insects.
  • In areas prone to termites:
    • Use non-cellulosic wall structures. That means avoid wood, straw, and other plant-based wall materials.
    • Treat any cellulosic material, such as wood framing, with a borate product to a minimum of 3 feet above the foundation.
    • Install a sand or diatomaceous earth barrier.
    • Install a steel mesh barrier termite control system. These mesh systems are installed around pipes coming up through slab and outside walls to keep termites from finding their way through gaps.

Ongoing Maintenance

  • Seal all external cracks, joints, penetrations, edges and entry points with caulking. Protect exposed foundation insulation with moisture-resistant, pest-proof cover such as fiber cement board or a galvanized insect screen.
  • Plan landscaping carefully. Avoid landscaping immediately adjacent to the house by ensuring all parts of mature plants will be at least 24 inches away from the home. Maintaining a buffer zone between plants and the house perimeter limits the habitat suitable for insect infestations. This has the added benefit of eliminating the need for irrigation close to the house, helping to prevent moisture leaking through the foundation.
  • Treat lumber and other cellulosic material with borate, a natural chemical alternative that controls insects but is safe for humans.
  • Install plants and landscaping elements that repel pests and encourage biodiversity. A yard that is dominated by one plant species, such as turf grass, is more susceptible to becoming a haven for a single type of insect. Biodiversity in a yard encourages a healthy, balanced ecosystem and lessens the risk of infestation.

A well-planned house that implements nontoxic pest-prevention strategies has taken an important step toward becoming a truly green home. LEED for Homes awards points for green pest controls. More information is available in the LEED for Homes Rating System and the LEED for Homes Reference Guide.

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Doug Smeath

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