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When you think of pests that attack from underground, subterranean termites immediately come to mind, particularly for those PMPs in the Southeast and Gulf Coast where these prehistoric insects thrive.

There is, however, another pest lurking beneath the surface that, while not as destructive as termites, presents a whole other set of problems. The American cockroach, Periplaneta americana, not only elicits a very negative response from customers if found inside a hotel room or commercial kitchen, but also poses a significant threat to food safety.

Cockroaches are known transmitters of bacteria and food-borne illnesses including E. coli and salmonella, and they readily spread them to food preparation and serving areas, as well as bathroom countertops and other sensitive locations.

Aside from the damage to a commercial establishment’s brand reputation, the prospect of customers falling ill after dining at an establishment where cockroaches are present in the kitchen is downright scary.

In many cases, cockroaches are a problem in these locations because of poor sanitation, excessive clutter, structural problems or uncooperative clients. While each of these factors can be a serious issue, even if they’re addressed, it doesn’t mean the cockroach problem will be resolved. That’s because something else may be the root cause of the problem, a harborage location that is often both out of sight and out of mind.

HIDDEN HARBORAGE. Sanitary sewers running beneath commercial establishments like restaurants and hotels are an ideal breeding ground for American cockroaches. Plentiful amounts of moisture, humidity and food debris make it a welcome environment for hungry, disease-laden cockroaches.

Treating sanitary sewers for cockroaches, however, isn’t always on a pest management professional’s cockroach treatment checklist.

“PMPs should care about treating for roaches in sanitary sewers because American and other large cockroach species often congregate in these locations,” says Dr. John Paige, senior scientist with the Environmental Science Unit of Bayer. “Controlling roaches at their source will prevent infestations inside structures that are attached to those sewers.”

Rentokil Steritech technicians use a hook-like tool to lift heavy manhole covers more easily.
Unfortunately, the number of products labeled for use in sanitary sewers is somewhat limited, restricting the options of PMPs. In response, Bayer recently took steps to expand the label language on its Maxforce Impact gel bait, conducting a field trial on an Orlando, Fla., resort property where one of its customers was experiencing a significant number of cockroach callbacks.

The property included a large hotel surrounded by several stand-alone structures and management received numerous complaints from guests about cockroaches inside rooms — a problematic, costly issue for hospitality clients — and on the grounds surrounding the buildings.

“The service provider was making perimeter treatments and applying baits and dusts around indoor plumbing, all in an effort to eliminate the problem,” recalls Paige. “But it persisted and they were getting five or six callbacks a week.”

Working with Paige on the field trial was Desiree Straubinger, a Board Certified Entomologist working for Rentokil Steritech, and the two agreed to walk the property jointly to see if they could uncover the root of the infestation.

With no evidence the roaches were coming from inside the buildings, Paige and Straubinger, a graduate of Purdue University with a degree in entomology, went outside and their curiosity led them to the property’s parking lot. They opened several sewer caps — which were approximately 40 to 50 feet from the nearest building — and discovered they were teeming with American cockroaches.

Paige and Straubinger applied small beads of Maxforce Impact a few inches below the sewer caps and after one week the cockroach population was reduced by 70 percent and the callbacks stopped.

THINK DIFFERENTLY. The experience Paige and Straubinger had with Maxforce Impact made them see the value of being proactive and rethinking their approach to combatting cockroach problems in commercial accounts. “So often PMPs treat the area where cockroaches are seen in an account but do not get to the actual source of the infestation which, as we learned, is not always indoors,” says Straubinger, market technical director for Rentokil Steritech. “After our work in Orlando, the first thing I ask one of our technicians coming to me with a cockroach problem is, ‘Did you check the sewer?’”

Maxforce Impact holds up well in harsh sanitary sewer environments, according to Bayer.

Even if there isn’t a large population in the sewer a preemptive application will keep roaches from foraging and gaining access to structures including hotels, resorts, multi-family housing and other commercial accounts that are connected to a common sewer system.

Another important part of the process is buying a tool that will allow technicians to more easily lift heavy manhole covers. Straubinger says her technicians carry a hook-like tool that municipal maintenance or sewer repair crews use to make the process easier and safer.

“If a client is experiencing ongoing problems with cockroaches and the source is not easily identified it is worth the time and effort to inspect the sanitary sewers,” advises Paige. “You can solve a lot of problems by treating one sanitary sewer.”

The author is a frequent contributor to PCT.