6 Tips for Controlling Difficult Cockroach Infestations

Persistent German cockroach infestations are frustrating. Even when you think you’ve done everything right, the pests just keep coming back. 

 

This costs you time, money and the customer’s patience. Clients may begin to question your abilities and even start shopping for a new pest control provider.

 

It needn’t be this way, says Eric Paysen, who recently helped tackle a real head-scratcher of a cockroach problem at a busy breakfast restaurant.

 

Paysen is technical services manager of Professional Pest Management at Syngenta, North America, and before that he was technical director of a large pest control company. 

 

Over the years, he’s learned tactics to help solve the most-challenging German cockroach problems.

 

When inspecting and treating for German cockroaches in a complex environment like a commercial kitchen, take a zone approach, says Paysen. For instance, start on the lefthand side of the front door and inspect and treat an arm’s length area from floor to ceiling; when you’re done in that zone, move to the next section. This will help prevent you from overlooking spots harboring the pests.

 

“You have to be super thorough” and “systematically look at every piece of that account,” says Paysen. If you take a haphazard approach, you’re likely to miss something. And even though that treatment may drastically reduce the roach population, the one pocket of roaches you missed eventually will reinfest all the areas you cleared, he explains.

 

The technician that Paysen helped at the breakfast restaurant was very systematic and did all the work that normally eradicates cockroaches, but the problem persisted.

 

Turns out, they were dealing with an unknown harborage site: an underground conduit housing soda syrup lines that ran from the soda syrup stack rack in the back to the fountain drink dispenser in the dining room. “Roaches were very deep into that harborage,” recalls Paysen.

 

The underground conduit was an unusual issue tied to the building’s construction. A more commonly overlooked harborage site is the void behind the kitchen cabinet toe-kick, which covers the recessed base of the cabinet. The toe-tick hides a large gap that exists between the false bottom of the cabinet and the floor. Other hard-to-locate harborage sites are voids within walls, equipment and motor housings.

 

“The areas that are easy to treat get treated, obviously. It’s the really deep harborages that are difficult to get materials into that get overlooked,” he reminds.

 

At the breakfast restaurant, Paysen used cockroach monitors or sticky traps to find the hidden conduit harboring the pests. 

 

Monitors were placed throughout the restaurant and as treatment progressed, cockroaches only were found in monitors near the soda syrup rack, which narrowed the hunt and eventually led him to the underground conduit. “Without the monitors, we probably never would have found that source of the infestation,” says Paysen.

 

When roaches are found in sticky traps, their harborage is nearby. “Roaches won’t travel very far. They’re not going to come out of their harborage and just roam all over the account. They’re going to stay within a few feet of their harborage” if food and moisture are available, says Paysen. Only in severe infestations will roaches get pushed out of harborages and spread out to other locations.

 

Ongoing monitoring lets you know if treatment is working or whether you need to “double down” and find the spots you missed, he says. Monitoring helps you decide when to transition from a cockroach cleanout methodology to a maintenance program with extended service intervals. And it alerts you early on to any cockroaches that get reintroduced.

 

“If you have monitors in the account and you find a roach, you might know they have roaches before your customer does. That’s a good situation to be in because then you can address the problem before your customer even knows about it. It’s always nice to be ahead of that curve,” says Paysen.

 

He recommends using monitors in commercial food handling establishments “100 percent of the time.” For apartments with recurring roach problems, put monitors behind appliances, under sinks and where plumbing penetrates the wall. 

 

“In heavy infestations, I always recommend hitting roaches with multiple formulations,” says Paysen. 

 

One go-to product is gel bait, which kills cockroach populations through transference: Adult roaches feed on the bait and return to their harborage. Nymph roaches, which rarely leave this space, feed on the vomit of the adults made sick by the gel bait. They also eat the feces of these adult roaches and dead adult roaches. As a result, the gel bait’s active ingredient is transferred throughout the roach population, killing more of the pests.

 

Dry flowable bait also kills roaches through transference. This dry powder is applied like insecticide dust to voids with a power or bellows duster. A new flowable bait from Syngenta has bait particles of various sizes that stick to the exoskeletons of roaches walking through treated voids. The foraging roaches eat the bait and also carry it back to the remote recesses where they breed and where it is eaten by other adult and nymph roaches.  

 

Using a dry flowable bait lets you treat “deep voids where roaches can become established that are kind of out of reach of traditional sprays and gel baits,” says Paysen.

 

When choosing liquid insecticide, “typically you’re going to get better long-term control if you use slower-acting products because they allow for transference,” says Paysen. A fast-acting liquid spray is best used when immediate knockdown of a heavy roach infestation is required, such as when a restaurant is shut down for health violations.

 

It’s a common misconception that cockroaches avoid gel bait if liquid residual spray also is applied. “We’ve done quite a few studies to debunk that. What we’ve found is that as long as you spray first and then apply your baits over dry residuals, you’re going to be okay,” says Paysen. Cockroaches may avoid gel bait if liquid insecticide is sprayed on top of it, as this affects its taste, so spray first and bait second.

 

To resolve the roach problem at the breakfast restaurant, Paysen used an insecticide foam, which expanded and traveled through the length of the infested conduit. “That finally put the nail in the coffin,” he says. 

 

“Resistance and bait aversion are very prevalent in cockroach populations,” says Paysen. An insecticide will not kill cockroaches that have mutated and developed resistance to it. Roaches also will develop a dislike for the taste of a gel bait that is served to them over and over again so they stop eating it. When either of these situations happen, treatment fails.

 

By changing up bait matrices, roaches don’t have time to develop a distaste. And by using a different active ingredient with a different mode of action and from a different class of chemical, you can kill any roaches that survived the first active ingredient you applied. As such, they can’t reproduce and create a new resistant generation. “By rotating, you stay one step ahead of the roaches and you are able to manage them long term,” says Paysen.

 

During roach clean-out operations for existing infestations, he recommends rotating products at each service visit or using two different active ingredients and bait matrices at a time. For maintenance services, monthly to quarterly rotations are ideal, but even twice-a-year product rotation will provide benefits.

 

 

Talking to the customer about sanitation “has been the bane of every (pest management professional’s) existence because it’s very difficult sometimes to get management, whether it’s food handling or apartments, to get compliance,” says Paysen.

 

While it is helpful for clients to prepare sites before treatment and to improve sanitation, it is not necessary.

 

“The reality is with modern pest control techniques and products, you can 100 percent eliminate cockroaches without the customer doing all those sanitation things that we would like them to do,” says Paysen.

 

The same goes for emptying kitchen cabinets and removing clutter, which is hard to do for people who live in small apartments. Moving items also can send roaches scurrying deeper into harborage areas. 

 

“It’s really not practical and it doesn’t help that much anyway,” says Paysen. Plus, most of the time you don’t get the level of prep that you’ve requested. “I think it’s better to be prepared to address the problem without the prep being done,” he says. Not requiring prep even could be a competitive advantage for pest control companies. 

 

Paysen urged PMPs to explore Syngenta’s cockroach assurance program to get more tips on developing a successful cockroach control protocol to control difficult roach infestations. The Syngenta program was developed and field-tested with PMPs and university researchers over a two-year period.