Cockroaches

German Cockroach

No one wants 'em. Yet they've persisted for more than 350 million years despite man's attempts to get rid of them. Without control, one pair of German roaches can expand to more than 2 million in less than a year. They like nearly any area humans like - especially where food, moisture and warmth are abundant.

Cockroaches prefer darkness and crawl into amazingly small crevices as small as the thickness of a coin. An adult cockroach can live for a month without food as long as water or moisture is present. 

Roaches carry and spread diseases. It's not unusual for bacteriologists to find salmonella bacteria (which causes food poisoning in humans) on the bodies of cockroaches. Additionally, cockroaches are believed to spread viruses and their presence can cause allergic reactions for many people, especially asthmatic children. 

What can you do if you find cockroaches in your living environment? The most important method of cockroach prevention and control is sanitation. Even a few crumbs that slip down beside a stove, for example, can serve as a gourmet dinner for several cockroaches for some time.

The German cockroach is by far the most important and usually the most common of the cockroaches. In addition to being a nuisance, it has been implicated in outbreaks of illness, the transmission of a variety of pathogenic organisms including at least one parasitic protozoan, and alallergic reactions in many people. This species has worldwide distribution. 

   
Adults about 1/2-5/8" (13-16 mm) long. Color light brown to tan except for 2 dark, almost parallel longitudinal stripes/bars/streaks on pronotal shield. Female darker than male, her abdomen broader. Rarely glide or "fly". 

Nymphal instars 1-2 with thorax dark brown to black but having pale lateral margins, meso- and metathorax pale/white centrally but with a continuous dark stripe near each margin; thorax and abdomen light brown ventrally. Later instars (3rd on) with 2 dark longitudinal stripes on pronotum continuous with dark abdomen, and abdominal segments usually with central areas pale on dorsum. Ootheca or egg capsule yellowish brown but usually two-toned, paler end attached to female; about 1/4-3/8" (6-9 mm) long, with length more than twice width; subdivisional furrows extending entire width; slightly bowed or arched; and with about 15-20 (range 925) eggs on each side. 

BIOLOGY. The female carries her ootheca until it is within 1-2 days of hatching, and then deposits it in a sheltered area/site. On the average, the female will produce about 5 oothecae (range 4-8), averaging 30-40 eggs (range 18-50) each. 

Developmental time (egg to adult) usually varies from 54-215 days, averaging about 103 days; under lab conditions of 80 degrees F/27 degrees C and 40% relative humidity, usually only 50-60 days are required. This means usually 3 to 4 generations per year, but up to 6. Adults live about 100-200 days (range 1-303). Established/mature German cockroach populations are typically composed of at least 75% nymphs. 

HABITS. German cockroaches are found throughout structures but show a preference for warm (70 degrees F/21 degrees C) and humid places. They are usually found in kitchens and secondarily in bathrooms, but infestations often occur in rooms where people eat and drink while watching television such as the den, bedroom, etc. Any crack or crevice located near a source of food and/or water is prime harborage, and they spend about 75% of their time in such harborages. First instar nymphs require a crack of about 1/32" (1 mm) whereas, adults require a crack of about 3/16" (5 mm) in width.

 

These cockroaches are most commonly introduced into buildings via paper products or paper packaging such as grocery bags, cardboard boxes, drink cartons, and via secondhand appliances such as refrigerators, televisions, VCR's, microwaves, etc. They have been observed to migrate from building to building on warm evenings, but this rarely occurs. Although uncommon, they can survive outdoors during the warm months. 

They feed on almost anything with nutritive value including all kinds of food, and such things as soap, glue, and toothpaste. 

Activity periods vary with life stage, age, and physiological state. For instance, reproducing females are quite active whereas, gravid (with ootheca) females are relatively inactive starting about the 5th day after mating and go only to food and water when necessary. Males spend most of their time in harborage, even at night. All nymphs become immobile and stay in harborage during the last 3 days of each instar while they prepare to molt. Hence, about 1/3 of the time the cockroach nymphs will not be found or found exposed during an inspection. 

Oriental Cockroaches

The female carries an egg capsule for about 30 hours and then drops or attaches it to a protected surface near food. On the average a female produces eight egg capsules, each containing 16 eggs which hatch within 60 days. The reproductive cycle of this roach is completed in 6 to 9 months.

Oriental roaches prefer damp, cool, dark areas. They are generally found in sewer drains, crawl space areas, basements, cellars, or on the first floor of buildings. They are also found in sewers and water meters. Infestations by this roach are most frequently found during spring (April and May) and fall (October). They may spend considerable time outdoors during warm weather.

Cockroach baits contain a slow-acting insecticide incorporated into a food attractant. Roaches locate and feed on the bait, typically contained in small, plastic bait trays, gels, granules and then they crawl away to die. Bait carried back to the nesting area also kills other roaches after being expelled in the sputum and feces. In contrast to liquid sprays or aerosols, cockroach baits require no mixing and it is not necessary to empty kitchen cabinets or cover food preparation surfaces prior to treatment.. Another advantage of cockroach baits is that they have essentially no volatility or odor