A significant amount of the commercial pest control services offered in the United States is directed at controlling the German cockroach in food facilities. Despite successes by many pest management professionals, a good many more often fail to provide consistent results in eliminating current infestations for their customers. Why does this occur?
Too often, this author has heard the excuse that the “chemical didn’t work” or the “cockroaches must be resistant.” Having had to help solve innumerable cockroach situations over the past 18 years, the author has found that the reason for failure in eliminating German cockroaches lies with not applying the insecticide where ALL the cockroaches are harboring. Not enough effort was made in discovering every active harborage. Overlooking one site is enough — the customer will still see cockroaches. It is interesting to hear someone brag about how many hundreds or thousands of cockroaches they killed in that restaurant last night. But which is more important, how many cockroaches you killed, or how many you left alive? Suffice it to say, customers care more about the latter.
So what are the keys to eliminating a cockroach infestation in a commercial food facility? This article will examine the issue by asking and answering 20 questions that illustrate the steps to success.
1. What is the basic rule to successful elimination of a cockroach infestation?
Investigate all the potential cockroach harborages to find and treat ALL of the active harborages.
2. Why do cockroach control efforts fail?
If a cockroach infestation occurs, it is because one or more active harborages — or sources — have been missed. For example, the author learned this lesson the hard way when working as a service professional. An institutional kitchen continued to experience cockroaches even after several visits. Each time, the kitchen was well prepared for service, and each time, few cockroaches could be found. On the third visit, the technician had the bright idea to check the items that were being wrapped in plastic bags in preparation for service. Sure enough, inside one meat slicer, more than 400 cockroaches were found. Several other “prepared” items were also infested.
3. I like to use wettable powders and “band in” the cockroaches. Eventually all the cockroaches will have to cross a treated surface, right?
The cockroaches may cross the treated surface but that doesn’t mean they will die. It may take 30 to 60 minutes to many hours of contact with a treated surface in order for the cockroach to absorb a lethal dose. The age of the deposit and the presence of dirt and grease both play a key role in extending the contact time necessary for results.
But why use formulations designed to treat surfaces when cockroaches spend most of their time in cracks and voids? You want to treat where the pest lives rather than where it crawls. For example, a kitchen has 20 active cockroach harborages. You treat all the corners, baseboards, inside cabinets, behind sinks, etc. You see a few cockroaches, maybe even treat them, but how many cockroaches are you sure you have killed when you walk out the door? What if you flushed and inspected and found 19 of those 20 harborages? You vacuum, you bait, you treat voids with dust. When you walk out of the facility, you know that you have made an impact. This can happen, especially in moderate to severe infestations in which cockroaches end up in less-preferred harborages that are often difficult to find. But which would you prefer to have — the situation where you might have left most of the infestation alive, or the one where you are pretty sure you got them all?
4. Where do cockroaches go when poor cockroach control services are applied?
A person providing poor cockroach control services will typically treat those areas/harborages that are easy to see and reach. To find cockroaches in a facility being serviced in this manner requires an inspection mirror and attention to hard-to-reach areas. For example, the easy-to-see cracks in the rear of a cabinet will receive treatment.
The inspection mirror directed to the cracks behind the front edges of the cabinet commonly reveal cockroaches. Another example are false ceilings. Cockroaches often move up there — even though the ceiling is a less-preferred harborage — following repeated space treatments or “foggings” (as they are commonly misnamed). We can “train” cockroaches to go where we haven’t treated. Look for those hard-to-reach areas to find overlooked sources of cockroaches.
5. What is the No. 1 site in commercial kitchens that is most often overlooked but is the cause of most continued infestations?
Wall voids. Think about it: In a commercial kitchen, the water pipes and electrical wires give cockroaches free reign through the walls. Numerous cracks or openings are usually present in these voids. Dark, humid, warm wall voids are in close proximity to food and moisture. Why wouldn’t cockroaches want to stay there in droves? If the wall voids behind the stoves, sinks and in the dishwasher are not drilled and treated, an important potential (and usually active) harborage is being missed. The author has been involved in a number of “unsolvable” cockroach infestations in restaurants where treatment of wall voids solved the infestation.
6. How should wall voids be treated?
In most cases, the voids should be drilled at a level 4 feet or lower from the floor. Cockroaches will want to be near moisture and food which is generally lower in the wall. In severe infestations, drilling at the ceiling level as well as at the 4-foot or lower level is usually helpful. Each void should be drilled, usually at 16-inch intervals. Be professional and drill holes in out-of-sight areas or in straight, level lines that are evenly spaced. The use of a chalk line can ensure a level line of drill holes.
The use of dust insecticides is usually the best way to treat wall voids, although some professionals use an aerosol machine (e.g. AgrEvo’s Actisol) containing the residual Conquer (Paragon Professional Products) and the IGR Gentrol (Zoecon Professional Products). The most important consideration is thorough coverage inside the walls. An electric duster can improve penetration of dusts, as will the “aerosol” dust products TriDie and PermaDust (Whitmire Micro-Gen).
7. What about hollow block walls? Does every void need to be drilled in these too?
No. Since block walls will have few holes for cockroaches to ingress and egress, only the voids to either side of plumbing penetrations or other such openings will require treatment.
8. Other than wall voids, what is the No. 2 area that is overlooked and serves as a source for continued infestation?
Electrical junction boxes and conduits serve as “bus depots” and “highways” for cockroaches around a kitchen and even to other parts of the building. In a recent case, the author spent an evening with a new service professional and visited a fast food restaurant. The manager of the facility pointed out two areas where cockroaches were seen. In the first area, the new professional was asked by the author what stood out in the area as a potential for cockroach activity. He correctly suggested the small refrigerator under the table. The refrigerator was pulled out and, no surprise: it was plugged into a junction box and conduit system. Inside the junction box were more than 100 cockroaches. These were removed by vacuuming and the area was baited with gel bait. If the refrigerator had not been pulled out (it takes effort) and the junction box cover removed (more effort), this source would not have been found and eliminated. This site and the other area pointed out by the manager (cockroaches living in debris under a table) were the only sources of cockroaches found.
9. Other than baits, how else can junction boxes and conduits be treated?
Dust insecticides are the best long-term choice for junction boxes. Be sure to use a plastic tip on the duster to avoid electric shock, or use one of the “aerosol” dusts. Only a very light amount of dust is needed and the dust should be directed into each conduit feeding into the box. Remove as many cockroaches as possible using a vacuum.
10. What is the No. 3 area that is overlooked? The false ceiling in a kitchen is a less preferred harborage for cockroaches, but they will move up into it if the population grows too large or poor cockroach control practices are employed. The ceiling is further from food and water than most German cockroaches want to be from sustenance. When these insects are in the ceiling, they will usually be over an area where food and water is available — typically above the dishwashing area, a stove line, or in the bar area in the front of the restaurant. 11. How should false ceilings be treated? False ceilings are tricky to treat because they are open spaces with few available cracks to treat. The first step is to inspect the ceiling to see which parts of the ceiling actually have activity. The effort is wasted if cockroaches are not even up there. The application of an encapsulated insecticide to the wall surfaces above the ceiling in infested areas is the best overall procedure. Cockroaches have to come down into the kitchen to eat and drink, so they will have to crawl down the walls (or columns). They are more likely to sit longer on the wall above the ceiling where it is dark than below the ceiling (where it would be easier to treat). This additional time increases contact with the residual, thus improving results. It is always best, however, to remove as many cockroaches as possible from above the ceiling with a vacuum. 12. I have treated every potential harborage including wall voids, conduits and the false ceiling. Why does my customer still see cockroaches? Something is being overlooked. Here are two examples: In one case, a storeroom continued to experience sightings of cockroaches but the service professional (the author) could find no activity on repeated visits. Finally, he decided to check the items being removed from the storeroom in preparation for service. Forty cockroaches were found living inside the ring on a large cardboard drum of powdered dish soap. This was obviously a less-preferred harborage but the cockroaches were there anyway. In a second case, every possible harborage had been treated in the salad prep area of a kitchen but cockroaches continued to be seen. Investigation by the author revealed hundreds of cockroaches living in the rim of the back side of several mirrors lying on a table in the middle of the prep area. No one had bothered to pick up the mirrors and turn them over. This discovery also solved the mystery of why cockroaches would be seen during banquets. The mirrors were used on the serving tables in the banquet rooms for the buffet line. The cockroaches were being carried out there in the mirrors and then carried back in after the function. No wonder the service professional could find no activity in the banquet rooms! In these two cases, it was assumed that cockroaches would be found in the tables, the walls or other equipment in the area where they were seen. But they weren’t. The cockroaches took advantage of harborages that weren’t being checked. The lesson: Try to look beyond the obvious and look at everything involved in the situation, including those items being carried in and out of the area where the insects are being seen. 13. What is the most important step in quick elimination of German cockroaches? The use of a vacuum to remove as many cockroaches as possible helps to achieve zero cockroaches more quickly than any other single step. Still, vacuuming alone will not eliminate an infestation. An integrated approach is critical to success. Wouldn’t your customer prefer to see a 50%, 60% or maybe even higher immediate reduction in his/her infestation? Vacuuming accomplishes this goal. Let’s examine the rationale for vacuuming versus treatment for some of the situations that might be encountered in a kitchen. You pull out a cabinet drawer and see 100 cockroaches crawling in the open in the corner. Would it be better to spray these insects and potentially scatter them, or remove them all with a vacuum and carry them out of the facility with you? The more cockroaches you take with you, the easier it will be for your other treatment procedures to deal with the rest. 14. Are baits all that effective in a commercial kitchen environment? Baits are an extremely effective cockroach control tool when used properly. But in order for a bait to work, the cockroach must find it and eat. To achieve total elimination using baits, every cockroach must eat the bait. Achieving this goal is often difficult at best, which is why baits must be combined with other treatment methods. 15. How should baits be applied for best results? The gel and paste baits, such as Maxforce Roach Killer Gel, PT 320 Avert Gel Cockroach Bait, Drax Roach Bait and Blue Diamond MRF 2000 are ideal because they can be placed directly into active harborages where cockroaches will more likely eat the bait. The smaller the placements, the better the results. Large placements are wasteful. Remember, gel baits must be placed into cracks and not on surfaces in commercial food areas. 16. Which dust insecticide is best to use? Drione, boric acid and Tempo 0.1% dust are all effective at controlling cockroaches in food areas. Drione and Tempo provide the quickest knockdown and results, but boric acid products are more economical. Many professionals use boric acid on follow-up services after they have used Drione or Tempo on the initial service. DeltaDust is not yet labeled for food areas, but when it receives such registration from EPA, it will be ideal for use in areas of high moisture, such as wall voids in the dishwasher area. 17. A big problem in restaurant kitchens is the use of stainless steel sheets on walls. What is the best way to treat cockroaches living behind these? Usually, the reason stainless steel is on a wall is because the wall has been damaged in some way (usually by excessive moisture), and it is easier to cover it with the steel than to repair the wall. Since moisture has been trapped behind the steel, the site becomes ideal harborage for cockroaches. In most cases, the edges of the steel are accessible so they can be pried away from the wall and the space behind treated using a dust insecticide or an aerosol machine. In most situations, this process will need to be repeated every month because the moisture and heat will be detrimental to any insecticide used. Any cockroaches chased out need to be removed by vacuuming. It is also important to drill and treat the voids inside these walls. Often, professionals treat one or the other but not both. If the stainless sheets are attached in a way that the edges are not accessible, a hole can be drilled into the steel and a dent puller (obtained at an auto parts store) can be used to pull the sheet away from the wall. Enough space is now created behind the steel to allow dust or aerosol insecticides to be applied, ensuring thorough coverage. 18. The dishwasher unit is too hot and wet to treat with residuals, yet cockroaches love it. How can this be successfully treated? Because no residual can stand up to the environmental extremes produced by a dishwasher unit, the unit itself should receive a directed contact treatment with a nonresidual aerosol and any cockroaches chased out removed by vacuuming. This process needs to be repeated on every service. 19. What about sites such as drains, motor housings and inside ice machines? How should these be treated? Drains will be treated in the same manner as the dishwasher unit — flush and vacuum on every service. The facility should be advised to clean such drains thoroughly and on a regular basis. Infested motor housings should be flushed and vacuumed. If cracks are available, a gel bait can be applied. Otherwise install a Maxforce station in the housing “box.” Ice machines can be treated only by vacuuming and the installation of a bait station in a secure site inside the machine where the station cannot fall into the ice-making machinery. In many cases, the station can be installed outside the vent holes where the cockroaches exit to go foraging for food. 20. Why should I use an IGR? Don’t they take a long time to achieve results? Yes, it takes many months for the IGR hydroprene (Gentrol) to affect a cockroach population. The IGR, however, is not to help control the existing infestation. Gentrol is applied for the inevitable future introductions of cockroaches. When new cockroaches arrive, the nymphs and subsequent offspring of the arriving adults will contact the IGR and then mature into functional nonreproductive adults. This process keeps the population at a lower level, where it will be easier to eliminate them using other methods. Research also suggests that IGRs stimulate feeding by some stages of German cockroaches to feed on baits. CONCLUSION. The theory behind cockroach elimination is easy — find all the active harborages and treat them directly (using both insecticides and non-chemical techniques). In practice, the difficulty arises in finding all of the active harborages. If you stay in the business long enough, German cockroaches will find new ways to surprise you. Train yourself to look deeper and see all of the aspects affecting the situation, especially the items that are moving in and out of an area where cockroaches are being seen. Good luck! Stoy Hedges is manager of technical services for Terminix International, Memphis, Tenn. Sidebar: RESEARCH UPDATE: FINDING CLUES IN COCKROACH DROPPINGS Cockroach droppings aren’t very glamorous, says Dini Miller, a doctoral candidate at the University of Florida, Gainesville, but they contain important clues to why cockroaches behave as they do. For the past few years, cockroach fecal material, or at least chemicals within it, has been the focus of a study Miller is completing. Miller has been working to show that fecal extracts contain an important trail pheromone that provides cockroaches with a “natural odor path” that shows them how to get from the harborage to a food and water source. “Instead of cockroaches wandering all over the house, no doubt they are following a path from hundreds of other cockroaches,” Miller explained, “trails that have accumulated from cockroaches using the same route, back and forth, night after night.” Miller has used fecal extracts to document that cockroaches do in fact follow a trail to food and water sites, as opposed to searching randomly for them. In a 4 x 4 foot arena that is shielded from light, Miller has designed a comfortable harborage in a plastic cup. Two paths forming a vertex are painted on sheets of white paper, and then the cup is placed at the vertex. One leg of the vertex is actually made up of fecal extracts; the other is simply water. “I pull the top of the cup off and the cockroach can choose which way it wants to go,” Miller said. “They could go anywhere, but they will run the extract nine times out of ten.” Cockroaches are tested individually, Miller explained, and the trick is to make sure the roach is calm before entering the arena. Cockroaches have five minutes to come out of the cup, and must be within one antenna’s length of the trail at all times. With further study, Miller observes, fecal extracts could have several practical uses in the pest control industry. “You could spray a trail of this against the baseboard, and cockroaches would follow that to a monitoring trap,” she said. Or the extracts could be painted within or near plastic bait stations. Interestingly, Miller's research indicates that the trail pheromone she is working with may not be the same as the aggregation pheromone which induces cockroaches to rest together in a harborage. “This pheromone is something else,” she said, which makes sense. “The aggregation pheromone is a volatile chemical that roaches detect in the air, then come and rest on it,” she explained. “This one they have to be in touch with, and they keep moving along on it.” Miller hasn’t identified what the trail pheromone might be made up of. For now she is completing her dissertation and plans to graduate in August. Her study, “Trail Following Behavior in the German Cockroach,” is expected to be published later this year. — Lisa Josof
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