American cockroaches can mess with your mind


June 20, 2016

  • To watch a large American cockroach emerge from the sewer is not unlike watching a horror flick when the monster first appears on the screen. Photo: Mark sheperdigian

    To watch a large American cockroach emerge from the sewer is not unlike watching a horror flick when the monster first appears on the screen.
    Photo: Mark sheperdigian

    American cockroaches invade buildings from the sewer, where they can cause chronic problems for years on end.

  • Sealing them out of the building can be an effective alternative to killing them after they enter.

The American cockroach (Periplaneta americana) is one of the large species that seem to plague large facilities and downtown buildings. They are known for traveling long distances and scaring the living daylights out of anyone who has never seen one before. Most pest management professionals (PMPs) focus on killing the cockroaches as close to the source as they can get, which means treating in and around floor drains. At best, you get a bunch of dead cockroaches and things will be quiet for a while — but it never lasts.

For many of these buildings, a solution might lie in a different direction. Considering the vast ocean of cockroaches living in the sewer below, there’s no sense in killing them as they enter the building. With diligent effort and a little cooperation, the cockroaches can be completely excluded from the building and long-lasting success can be achieved. It’s true that the task is large, but don’t mistake difficult for impossible.

Lay the groundwork

Start the process with a map of the building and insect monitors to chart the population. With floor drains comprising the majority of entry points, begin by fitting them with one-way drain valves. If no valves can be found to fit all the different drains, they can be screened with aluminum screen. It may be necessary to inspect them regularly to ensure they remain free of debris, but this is normally not a big problem.

Photo: Mark sheperdigian

Photo: Mark sheperdigian

Continue the program by using baits or contact insecticides to eliminate any cockroaches living within the building. Use building plans to identify forgotten drains, or careful inspections if no plans exist. The best tools are experience, an inquisitive mind and imagination.

In old buildings with chronic water problems, there can be a space under the slab called subsidence. If there is a population of cockroaches living there, you can find them using the information from insect monitors. If there are multiple breaks in the drainpipes and the slab is also broken up in many places, you may need to embark on a search-and-repair journey to re-establish the integrity of the concrete floor. In some buildings, this is truly a mammoth task, but taken one at a time, you will see the incidence of cockroaches in the insect monitors diminish over time.

Be prepared to use baits, dusts and contact insecticides to eliminate cockroaches from voids while the process continues. Persistence will pay off.

One more thing: In southern regions, American cockroaches can live on the exterior and invade from there. This requires a separate effort, which includes an exterior program of eliminating the exterior reservoirs … but that’s a discussion for another day.

You can reach Contributor Mark Sheperdigian, BCE, at

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