Mar 31, 2012 – Big Roaches


I have a restaurant with Oriental and American roaches. They were bad when they called me in January when the temperatures outside were freezing. I can't locate where they are coming from and they are on a septic system. Could that be the source and if so what is the answer to treating?


These two large roach species are well known for living outdoors, within underground passages such as storm drains and sewers, and in other protected places at or below ground level. I would agree with you that finding many of them outdoors during the coldest part of the winter is unlikely, although with the warming weather this could once again be a possible source for them to replenish those inside. However, restaurants probably offer plenty of places for these large roaches to hide and live during the winter months, coming out to feed on whatever the restaurant is making available to them. I will admit that I am not an expert on how a septic system is set up, but my thought is that it should be a closed system. There should not be any open routes from the septic tank back into the building, as that would just seem to be a bit unsanitary and to allow odors to come into the building. 

I have always preached that large roaches cannot swim through the P-trap in plumbing lines, but I have been corrected on this by a couple of people who have personally watched American roaches crawl down into a drain, continue into the water in that P-trap, and either not come back out or come back out a few minutes later, seemingly healthy for the experience. They did not swim so much as they walked along the inside of the pipe, but the water definitely was not a perfect barrier. I now suggest that I cannot see a LOT of these roaches making their way up from underground systems, through the P-trap, and into the building, but live and learn I guess. 

There also are stories of American roaches living comfortably outside in the winter, right under the snow but in a location that was staying warmer than the ambient air temperature. When uncovered they scurried away quickly, showing that they could indeed be alive and active outside in the winter, and possibly entering the structure. In your case though, maybe we should consider the more obvious reason the roaches are present, and that could be harborage points inside the restaurant. Does this place have a basement? Is there any lower area of rooms or storage compartments they could live in. They may be inside walls and moving around along pipes. What kind of heating does the restaurant have, and could there be ducting within the slab or beneath the floor that the roaches move through. 

I suggest you start with two principles - monitoring and sanitation. I would assume that you already have done the sanitation inspection of this restaurant and documented all of the sanitation issues you found, and discussed these with the management. The roaches don't require a lot of food, but they do need food, and every scrap of food left available will support them. Every area that you can get cleaned and keep clean at night will put the roaches under that much more stress to find other food resources, and this moves them around. Monitoring using plenty of glue traps will help you to determine where the roaches may be coming from. The traps can be placed in hidden places and within stations so that patrons of the restaurant do not have to see them, but these are good tools for telling you more about the population of the bugs there. 

You can also treat cracks and crevices where you believe the roaches may be hiding, using a labeled residual product. Granular baits seem to be very acceptable to the large roaches, and these can be placed within wall voids or in stations. This might also be the time to make a careful inspection of the outside of this building to identify all the possible entry points for the roaches, which presumably came in from the outside originally. These can be permanently closed to keep the roaches and other bugs outside, and it can be done in stages so it is less formidable of a task. 

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