What method is effective for controlling American cockroaches in drains?

Applying silica gel with a powder duster is effective for controlling American cockroaches in drains because silica gel works by dehydrating the insects upon contact. American cockroaches often harbor in damp environments like drains, and using a powder duster allows for the controlled application of silica gel in those hard-to-reach areas.

The gel adheres to the insects as they traverse through treated sites, and since it is a desiccant, it disrupts their ability to retain moisture, ultimately leading to their death. This method is advantageous because it targets the problem directly in the cockroaches' harborage areas and, unlike liquid insecticides, does not create a residual moisture that could attract more pests.

Other methods, such as chemical fogging, might disperse an insecticide broadly but are not specifically tailored for the confined spaces of drains. Simple water flushing may remove some cockroaches temporarily but does not provide long-term control or prevention. Using essential oils can have some repellent qualities, but they are generally not as effective as silica gel for eliminating existing infestations.