Why can some treatment fail when using the perimeter method on invaders?

Why can some treatment fail when using the perimeter method on invaders?

• A. Perimeter treatments can fail when applied after many insects have already crawled into wall voids.
• B. More effective perimeter treatment at edge of property.
• C. Perimeter treatments are always successful.
• D. Perimeter treatments never fail.

Answer: (A)

Perimeter treatments create a chemical barrier around the outside of a structure to keep insects from entering or to kill those that contact treated surfaces. This approach assumes pests are near exterior entry points or in accessible areas, so they encounter the barrier as they try to get in or as they move along the exterior. The reason this method can fail is that if many insects have already crawled into wall voids, behind siding, in crawl spaces, or other interior harborage, they’re out of reach of the exterior barrier. Those interior populations can continue to survive, reproduce, and eventually move back into living spaces, undermining the perimeter treatment. In short, once invaders are already hidden inside the structure, a perimeter-only approach may not reach them. To improve success, inspections and treatments may be needed inside the structure as well (and sealing gaps to limit harborage), rather than relying solely on the exterior barrier.

Perimeter treatments create a chemical barrier around the outside of a structure to keep insects from entering or to kill those that contact treated surfaces. This approach assumes pests are near exterior entry points or in accessible areas, so they encounter the barrier as they try to get in or as they move along the exterior.

The reason this method can fail is that if many insects have already crawled into wall voids, behind siding, in crawl spaces, or other interior harborage, they’re out of reach of the exterior barrier. Those interior populations can continue to survive, reproduce, and eventually move back into living spaces, undermining the perimeter treatment. In short, once invaders are already hidden inside the structure, a perimeter-only approach may not reach them.

To improve success, inspections and treatments may be needed inside the structure as well (and sealing gaps to limit harborage), rather than relying solely on the exterior barrier.