FOCUS ON COCKROACH CONTROL: Big Roaches, Big Jobs

Of all the structure-infesting cockroaches, no species has such a prominent place in the American psyche than the American cockroach. The largest of our pest cockroaches, this species has provided many a “fish story” to nearly any non-pest professional who has encountered one. In my 23 years in the business, I have been regaled by customers, coworkers and friends who claim to have seen the world’s largest cockroach right in their own home, business or street. Holding their fingers 3 to 4 inches apart, these well-meaning souls swear that the cockroach they saw was “this big.” No amount of reasonable explanation as to the impossibility of these occurrences can dissuade their claims. But I do have an example to help my argument.

Throughout the past few years, different companies  from around the U.S. have sponsored “largest cockroach contests.” The various contests have offered hundreds (or even thousands) of dollars to the person who finds the biggest roach. Guess what? An American cockroach usually wins and they are always about 2 inches long. One would expect that if a 3- to 4-inch roach existed out there, someone would have entered it in one of those contests. But, of course, the textbooks are correct — they say the American cockroach  measures up to 2 inches long. We entomologists are consistent in measuring and documenting facts about the creatures we study.

Still, 2 inches is a big bug, particularly if it’s in someone’s house or office. Floridians are proud of their “palmetto bugs.” These insects are a prime reason Northerners quickly sign up for regular pest control services after they move to Florida. Up north they never saw the need for such services until coming face-to-face with “monster” cockroaches in Florida. These persons likely have seen one or two in their native states, referring to them as “water bugs,” but it is likely the frequency of the encounters increase upon them moving to the South.

The American cockroach, however, is not confined to Florida. It is one of the two species common to every state in the continental U.S. ( the German cockroach is the other). It tends to be more of a commercial pest in colder climates and a pest of both residences and commercial buildings in warmer states. The American cockroach is highly adaptable as long as it has its required living conditions in which to breed: high moisture and warm temperatures in a dark void. Sewers definitely fit these requirements as do steam tunnels, basements, pipe chases, tree holes, block walls and piles of lumber, bricks, flagstones and debris located outside.

MORE AND MORE ROACHES. Female American cockroaches are rather prolific in producing egg capsules. A female might create one ootheca per week, on average, for a year or more. In one study, a female produced oothecae every four days although the interval lengthened in cooler temperatures to 12 days. A female may produce 50 or more oothecae in her lifetime; The maximum recorded was 90 capsules. Many of these are infertile, however.

Given these numbers, the maximum number of American cockroaches originating from one female in a year’s time is about 500 — far different than the German cockroach where a single female might produce seven capsules in her lifetime but result in 30,000 or more descendants after 12 months. Why the huge discrepancy? Three reasons: 1) an American ootheca carries about half the eggs of the German — a maximum of 16; 2) American cockroaches drop their capsules in protected sites then abandon them to possible predation — German females carry and protect their ootheca until just before the young hatch; and 3) American cockroaches take about a year to develop from egg to adult — German nymphs can reach maturity in as little as 45 days. The German female’s first brood of young begins producing their own offspring within two months, the American’s don’t begin often until a year later.

The above observations offer a point to be learned. In the mid-1980s, I inspected a four-star restaurant that was under regular pest control services but was not experiencing any particular pest problem. To shorten the story, this restaurant was thought to not have a crawlspace because it had a concrete slab floor — construction most common to that area. Several days before this inspection, a piece of equipment in the restaurant was removed revealing a metal door in the floor of the kitchen. Investigating what was underneath, I discovered there was a crawlspace — one filled with American cockroaches. The sound of thousands of tiny feet scurrying across the sand and along the walls was clearly audible upon lifting the door. Further investigation revealed the drain line leading from the garbage disposal was broken and had been depositing food-laden water beneath the building.

Of particular interest was the fact that rarely was an American cockroach seen by restaurant personnel or the service professional in the restaurant — despite about 10,000 cockroaches in the crawlspace underneath. The likely reason was the abundant source of food present and available space (or carrying capacity of the harborage) had not yet been exceeded. The cockroaches therefore had no reason to venture above into the building.

How long though had the drain line been broken so that so many American cockroaches could have occurred in this one 2,500 square foot, 30-inch tall space? If one were to do the math and calculate that beginning with one gravid female, the population was in place for at least four years prior to its discovery. More likely, since the drain line was broken allowing drainage into the crawlspace, American cockroaches living in the sewer to which the drain line was attached immigrated into the crawlspace and stayed. More likely, I would conclude the drain line had been broken at least one to two years, permitting the population to occur both by reproduction and immigration.

As a professional dealing with American cockroaches, it is important to consider the numbers of an American cockroach infestation. Larger numbers suggest factors that might lead to persistent infestations and invasions of a particular structure, like the crawlspace described previously. In another case in Atlanta, a neighborhood was plagued by huge numbers of American cockroaches that were ultimately traced to an improperly operated landfill a short distance away. Large numbers of American cockroaches usually mean an alternative source that may or may not be located on the customer’s property.

In most situations, the numbers seen will be one to a few on a regular basis. American cockroaches have a habit of showing up irregularly in many areas of a building — they may not be seen in the same room twice. This species will forage great distances (for a cockroach) from the primary harborage. Remember, American cockroaches require high, stable humidity in their harborage. A ready food source may not be located in close proximity, thus prompting long treks to supper. It is not uncommon for an American cockroach to venture 50 feet or more nightly to a standard food resource. Remove these food resources and you may cause the cockroaches to forage more actively, thus causing them to be seen in areas where they would not be expected — i.e., an office on the sixth floor of a building (try explaining the “why” to the attorney who resides in the office).

The key to successful, long-term control of American cockroaches is to focus on finding the harborages where high humidity and warmth are consistently present and discerning the pathways the cockroaches might be using to navigate from the harborage to the points where they are seen in the building.

PEST CONTROL IN HOMES. In home infestations, the source is usually not difficult to find. In the South, inspections should begin outside. Tree holes are the native habitat of this cockroach outdoors, but the same conditions found in such holes might be present elsewhere. For example, Dr. Rick Brenner of the USDA in Gainesville, Fla., discovered the mircoenvironment in a poorly ventilated attic closely matched those of a tree hole. This fact explained why attics without good ventilation harbor so many more cockroaches. Brenner’s research proved that the simple act of ventilating a home attic deterred cockroach infestations. The same findings held true for crawlspaces.

One of the important long-term recommendations for homeowners in the South is to install adequate ventilation in attics and crawlspaces. Such recommendations can also prove a ready source of additional income for an enterprising pest control company. Companies have long offered installation of foundation vents and vapor barriers in homes, but attic ventilation is a somewhat untested venture for our industry. One must keep in mind that an adequate soffit vent must be present together with a way for the air to move up through the soffits and exit through the roof. Brenner’s research showed ridge vents worked the best in thoroughly venting an attic. Installing attic vents is not difficult, but certain tools and training are required. Check with a manufacturer of ridge vents for instructions on installation and cost estimation.

Sites harboring American cockroaches around a home are not difficult to uncover using a flushing agent (pyrethrins aerosol). Common sites to find cockroaches include tree holes, cracks by the soffit, pipe openings, loose landscape (e.g., bark) mulch, flagstones, dog houses, sheds, unventilated porch roofs, breezeway roofs, exposed stud walls in garages, firewood piles and any pile of lumber, bricks, leaf litter or debris. Cracks or voids that harbor cockroaches can be treated with a dust product (e.g., Drione, Tri Die Bulk Dust, DeltaDust). Wood piles, tree holes, landscaped areas, etc., can be treated with a granular insect bait (e.g., Niban, Maxforce Insect Bait).

In most cases involving attic infestations, professionals attempt a dust application to control the infestation. The problem with this is twofold. First, being able to treat with dust every area in an attic where cockroaches could be located is not likely without covering the entire attic. To do so means the expenditure of a larger amount of dust and the time necessary to make the application. Second and more important, extensive dust applications in attics (and crawlspaces) are viewed with suspicion — and rightly so — by plumbers, cable installers and other workmen. In this day and age, who wants to crawl around in some unidentifiable white dust? Attic (and crawlspace) dusting for the control of American cockroaches and other peridomestic species is not recommended. There may be situations, however, where you might acceptably apply small amounts of dust beneath insulation, into a soffit or into cracks.

The far better approach is to use granular insect baits where these cockroaches are found. Brenner discovered he could eliminate a current infestation of peridomestic cockroaches using only baits applied as close to or into active harborages. His research proved that such cockroaches are found most often in the soffits during the summer and in the peak of the attic during the winter. Take these facts into consideration to make effective bait applications in attics.
 
COMMERCIAL ACCOUNTS. Dealing with American cockroaches in commercial structures can be frustrating due to the tedious and time-consuming inspections and investigations that may be needed. The key partners in tracking the pathways and possible breeding/harborage sites inside large buildings are the building engineer(s) and maintenance departments. These persons know the building and its construction better than anyone. A good report and effective questioning of such persons can narrow the areas requiring investigation.

Begin with a copy of the floor plans for each level of the building. Plot each cockroach sighting and the sites where you have found activity. Does a pattern of activity emerge along one side of the building or among two or more floors? If so, the engineer should be able to help connect the dots with possible pathways.

Key sites for American cockroaches in commercial buildings include boiler rooms, basements and sublevels, steam tunnels, pipe chases, elevator shafts, sump pumps and flat roofs.

Many professionals ignore manholes located on commercial properties. At the very least, these should be checked for cockroach activity regularly, possibly monthly during the summer for buildings that have chronic American (and Oriental) cockroach problems. If treatment with boric acid is not possible due to state or local restrictions, gel cockroach baits can be used to reduce the numbers of cockroaches.

In addition, you may want to maintain monitors in potential American cockroach harborages, such as boiler rooms, laundry areas, outside foundations and even roofs. An effective monitor for these cockroaches in wet environments and roofs are simple can traps. One-quart paint cans purchased at a hardware outlet are ideal. Tape strips of masking tape up the sides of the cans to permit easier access by cockroaches into the cans. Rub a thin layer of petroleum jelly along the top, inner lining of the can and bait the can with bread soaked in beer or inexpensive wine. Place the cans along walls, in corners and other potential cockroach foraging pathways. Insects attracted to the “bait” crawl into but cannot escape the trap due to the petroleum jelly layer. Bear in mind, outside, animals such as raccoons and rats might raid the cans for the bread and even trapped cockroaches. Can traps can be placed to determine the extent of an infestation and to narrow the search area when pinpointing key harborage sites.

Once the harborage sites are known, follow accepted treatment techniques using label directions. For example, cockroaches living in a block wall could be treated with a dust product or with a granular insect bait. Piles of debris/items outside a foundation or in a Dumpster area are best treated using a granular insect bait and recommending to the customer the debris, lumber, bricks, etc., be removed as soon as possible.

SUMMARY. Like any pest infestation, those involving American cockroaches require analysis of the situation to pinpoint active harborages and contributing conditions. Direct treatment of these harborages produces the most effective short-term results. Correction of contributing conditions either by the customer or by the professional hired by the customer are necessary to effect long-term relief from these bothersome pests.

The author is manager of technical services for Terminix International, Memphis, Tenn. He can be reached at shedges@pctonline.com.