[Cockroach Control] German Cockroaches: The Industry's 'Bread and Butter'

Editor’s note: The following information on German cockroaches has been excerpted from Norm Ehmann’s newly published book “Adventures Through The World of Entomology.” The book blends technical information with gritty, down-to-earth knowledge geared to everyone from seasoned veterans to the industry’s newest workers and can be ordered from Univar reps at 800/808-4897 or online at www.pestweb.com.

Let’s consider for a moment the concept of “biological potential” in German cockroaches. Biological potential means: “How long does it take for a population to get very large?” and “How large can it get?”

The answer to biological potential depends upon several factors: (1) How many eggs are in an average capsule? (2) How many egg capsules will a female produce on the average in a year? (3) How long does it take for the first instar nymph to become an adult cockroach capable of mating and producing another generation? The answers to these questions are not always precise, but we can get a good idea of biological potential if we just deal with averages.

A LITTLE MATH. A look at some formulas points out that the real key to “biological potential” rests upon the length of time from egg to mature adult. Let’s do a little math to see why we can make such a statement.

Basic formula for biological potential:

Number of embryos per oothecae x Number of oothecae produced per year = Number of mature adults per year.

If we start with one pregnant American cockroach that has 16 embryos in her egg capsule and she lays 30 egg capsules, we will have 16 x 30 = 480 mature adults in about a year.

If we start with one pregnant Australian cockroach that has 24 embryos in her egg capsule and she lays 30 egg capsules, we will have 24 x 30 = 720 mature adults in about a year.

If we start with one pregnant Oriental cockroach that has 16 embryos in her egg capsule and she lays 15 egg capsules, we will have 16 x 15 = 240 mature adults in about a year.

If we start with one Smokybrown cockroach that has 20 embryos in her egg capsule and she lays 15 egg capsules, we will have 20 x 15 = 300 mature adults in about a year.

If we start with one pregnant Brownbanded that has 16 embryos in her egg capsule and she lays 15 egg capsules, we will have 16 x 15 = 240 mature adults in six months. If half of these adults are females and they all mate, we will have 120 pregnant females at six months. If each of these females lays 15 egg capsules, each containing 16 embryos, we will have 120 x 15 x 16 = 28,800 mature adults in about a year.

If we start with one pregnant German cockroach that has 30 embryos in her egg capsule and she lays 5 egg capsules, we will have 30 x 5 = 150 mature adults in three months. If half of these adults are females and they all mate, we will have 75 pregnant females at three months. If each of these females lays 5 egg capsules, each containing 30 embryos, we will have 75 x 5 x 30 = 11,250 mature adults by the time six months has elapsed. If half of these adults are females and they all mate, we will have 5,625 pregnant females at the six-month time frame. If each of these females lays 5 egg capsules, each containing 30 embryos, we will have 5,625 x 5 x 30 = 843,750 mature adults at the nine-month period. If half of these adults are females and they all mate, we will have 421,875 pregnant females at the nine-month time frame. If each of these females lays 5 egg capsules, each containing 30 embryos, we will have 421,875 x 5 x 30 = 63,281,250 mature adults by the end of the year. That’s more than 63 million cockroaches, folks, beginning the year with one pregnant female.

OUTPACING THE COMPETITION. Anyone can do the math and see that the German cockroach, in a period of one year, has out-produced the American cockroach by 131,000 times; the Australian cockroach by 87,500 times; the Oriental cockroach by 252,500 times; the Smokybrown cockroach by 210,000 times and the Brownbanded cockroach by more than 2,187 times.  If the same analysis continues for several years, the geometric progression of numbers for the German cockroach becomes astronomical. And that is what is meant by high biological potential. One of the reasons for the success of the German cockroach worldwide is that it just out-produces other structural pest cockroaches. Suppose that one of the food processing or servicing units that you have taken over for pest control has 100 female cockroaches in it at the time you take it over. Can you see what could happen if your control procedures are not adequately carried out?

Female cockroaches of different species handle the deposition of their egg capsules in slightly different manners but most of them either drop their egg capsules on a flat surface, hide their egg capsules in loose camouflaging debris or stick their egg capsules on vertical surfaces within a few days after they are formed. The German cockroach, however, carries her egg capsule protruding from the end of her abdomen until just before it is ready to “hatch.” Then she drops it on a smooth horizontal surface. (If you see a female German cockroach carrying her very mature egg capsule and it is protruding from the end of her abdomen and is almost as large as her abdomen itself, you just have to think “ouch!”) If the egg capsule is removed from her abdomen a day or two before it is ready to hatch, it will not hatch. A rule of thumb that I always remembered was: If you found a cockroach egg capsule in a home in the silverware drawer in the kitchen, you were probably dealing with a German cockroach infestation. However, if you pulled that silverware drawer out and looked at the underside of the drawer and found cockroach egg capsules glued to the undersurface, you were probably dealing with a Brownbanded cockroach infestation.

The nymphs that hatch from German cockroach egg capsules grow up in stages called instars. When a first instar cockroach is ready to become a second instar cockroach, it casts its exoskeleton and becomes a size larger and a step closer to adultery — excuse me, I mean adulthood. The casting of the exoskeleton is known as ecdysis.

It is a fact of life that German cockroaches are liable to be found in most food processing and serving establishments. By serving establishments I mean restaurants — all the way from fast food purveyors to upscale restaurants of all descriptions. A few years ago, while attending the Annual Purdue Pest Control Conference, I listened to a paper presented by Dr. Austin Frishman that brought out the fact that cockroaches collected from a wide assortment of restaurants in a major city in the U.S. were found in the laboratory to have staphylococcus, streptococcus and Escherichia coli organisms on the sticky pads on their “feet.” You will recognize that these are pathogenic organisms — (pathos = sickness, genic = to cause). I cannot help but believe that German cockroaches, when wandering around on food or food preparing surfaces in the still of the night may be depositing some of these organisms in or on food.

Thus it is, in my mind, of extreme public health importance that cockroach levels in food establishments be kept to a minimum. A zero tolerance level is ideal, but not feasible because there are many re-infestation routes. Continued surveillance is our only salvation and it should be the norm for every service technician to be familiar with and to use sticky board monitoring techniques at each of the food processing and serving properties under his jurisdiction — no exception.

CLOSING THOUGHTS. Before closing out this adventure, I would like to mention one infestation of German cockroaches that stands out above all of the hundreds of infestations I have observed in the 48 years that I have been associated with the structural pest control industry. This infestation was discovered in and under a small radio on the night stand next to the bed of a helpless 96-year-old woman in a convalescent hospital, waiting there to die. This woman was my mother, and the fact that this infestation existed made me sick to my stomach.

Putting Maxforce FC Magnum to the Test

Following the launch of Maxforce FC Magnum in summer of 2007, Bayer Environmental Science commissioned a scientific study to demonstrate the bait’s speed and efficacy against German cockroaches in actual use conditions in the field.

Working together, Joe Snopek and Scott Saunders of Ragan Pest Management Services and Dr. Gary Braness, Bayer field development and technical service representative, selected a low-income apartment complex in Kansas City, Mo., for the test. Ragan Pest Management Services had recently acquired a housing complex account in Kansas City that was overwhelmed with German cockroaches.

All apartments used in the study included three upstairs bedrooms, two bathrooms, a living room, kitchen and utility room. On day one, the team set out to determine which apartments to treat for the test by placing six traps (Trapper Monitor & Insect Trap, Bell Laboratories) in the same locations within 20 apartments: Cabinet above sink (kitchen); cabinet under sink (kitchen); beside or under the refrigerator; beside or under the stove; behind the toilet; in the utility room.

Following the first 24-hour monitoring period, the team selected 10 test apartments all in the same building with large cockroach populations. In each test apartment, the number of cockroaches trapped ranged from 35 to 631, with a mean of 231 cockroaches per six traps. Most of the cockroaches in the apartments were trapped near the refrigerator and stove. “Many of the trapped cockroaches were nymphs, which indicated to us that a host of eggs had recently hatched and that the situation was getting out of hand,” Braness said.

That same day, the 10 most heavily infested apartments were treated with Maxforce Bait Injectors loaded with Maxforce FC Magnum. “We made traditional bait placements, according to label directions, in each apartment,” Braness said. In the kitchens, bathrooms and utility rooms, the team applied crack and crevice treatments of Maxforce FC Magnum.

The day after treatment, the team set out new monitors in the same places as the pre-treatment survey to determine the level of control after 24 hours. After only one day, the cockroach population had been reduced by nearly 74 percent. The team documented dramatic reductions in cockroach activity and observed large numbers of dead cockroaches present in each apartment. Two days after treatment, the population had crashed by 83 percent. By 30 days after treatment, the cockroach population was further reduced by nearly 96 percent. “We were very happy with the results, and so were our customer and the apartment complex’s residents” Snopek said. — Gordon Morrison, Maxforce insecticides market manager, Bayer Environmental Science

BASF Outlines Pest Control in Food Plants

A new white paper from BASF aims at helping pest management professionals better understand the unique challenges presented by food processing facilities.
The white paper, titled “Pest Management in Food Processing Facilities: A Resource Guide,” breaks down the areas PCOs should focus on when servicing food plants, as well as the pests they will most likely encounter and the various products that are available to them.

William A. Kolbe, market development specialist with BASF and a board certified entomologist, said the key to success in a food plant account is establishing and maintaining good communication between the technician and the staff at the plant.

“In my mind, the major issue in food processing and food handling is they have to be a partner with the food processor,” he said. “The technician that goes in there has to be certified (and) they should be thoroughly trained in food processing. To really be good in food processing, to do pest management to what the food processors want in today’s age, you have to become a partner with them.”

That partnership means learning not only what pest pressures exist at the plant, but also how the plant functions — including hours of operation, employee behavior and the programs in place to prevent food contamination.

“Whoever you are, if you’re going to excel in food processing, you have to devote the time and the energy and the training to the technician that goes in there,” Kolbe said.

You can download a copy of the white paper at www.phantomhome.com/food.