Oriental Cockroach

Scientific Name:Blatta orientalis Linnaeus (Insecta: Blattodea: Blattidae)

Introduction:

The origin of the oriental cockroach, Blatta orientalis Linnaeus, is uncertain, but it is thought to be from Africa or south Russia. It is a major household pest in parts of the northwest, mid-west, and southern United States. It is also sometimes referred to as the "black beetle" or a "water bug" because of its dark black appearance and tendency to harbor in damp locations.

Description

The oriental cockroach is approximately 1 inch long (22 to 27mm) and dark brown to black. Males have wings covering 3/4 of their body, and the female has very short (rudimentary) wings. The inner wing folds like a fan and is membranous. The outer part of the wing is narrow, leathery and thick. The styli between a pair of jointed cerci can identify the male. Both the male and female are flightless.

Oriental cockroaches thrive in port cities throughout the world. They can be found throughout the United States, as well as in England, Europe, Israel, Australia and South America. Oriental roaches prefer cool, damp locations, so they are typically located in basements and cellars. Oriental cockroaches crawl around service ducts, toilets, bathtubs, sinks, radiators and pipes.

Life Cycle

On average an adult male oriental cockroach will live 110 to 160 days, whereas the adult female can live anywhere from 35 to 180 days. During that time, a single female oriental roach can produce approximately eight egg cases, or ootheca, with approximately 16 eggs per case. Approximately 30 hours after she has produced the egg case, she will drop it in a protected area where it will stay until the young hatch. The development time for the oriental cockroach is greatly affected by the season. In the warmer months, the time needed to develop from an egg to an adult may take as few as 200 days. However, when the weather becomes colder, or during the late fall and winter months, it can take as many as 800 days for the cockroaches to go from egg to adult.

A female oriental cockroach produces an average of eight egg capsules per lifetime. Each egg capsule or ootheca contains about 16 eggs that are lined up vertically, two by two in the egg case. The egg capsule may be carried from 12 hours to five days and then deposited in a warm sheltered environment where food is readily available. The incubation period for the oriental cockroach is a bout 42 to 81 days. The female gives no assistance to the young. Nymphs go through seven molts before becoming adults, which takes approximately one year. An adult B. orientalis can live from 34 to 180 days, and pairing takes place at any season.

Egg Capsules: Egg cases, or oothecas, of the oriental cockroach may appear dark brown or reddish in color and almost 8 to 10 mm in length. Each egg case, which can hold approximately 16 eggs, is dropped by the female into protected areas, almost 30 hours after it is produced.

Odor: In areas where large populations of oriental cockroaches are present, a musty odor can be detected. This odor is a result of chemicals that are secreted by the insects that are used to communicate within the population.

Habits

Blatta orientalis is common outdoors, and lives in warm damp shady areas near the ground or any area containing natural debris. It will often seek refuge indoors when a drop in temperature occurs, but is still quite tolerable of cooler weather. The most common areas to find B. orientalis are basements, crawl spaces, areas between the soil and foundation, underneath sidewalks, in sewer pipes, in floor drains, and under sinks or any other damp cool area in the house. The roach travels through the structure on plumbing pipes. Outside the house they sometimes aggregate near or under garbage cans. The species tends to be seasonal, with adults appearing in spring and summer. When large numbers of roaches occur, overcrowding can lead to the mass migration of roach species such as the German cockroach, Blattella germanica, the American cockroach, Periplaneta americana, and the oriental cockroach.

Diet

Primarily an outdoors species, oriental cockroaches are well adapted for surviving in the natural environment. Most outdoor populations can be found living beneath the mulch in landscape beds, in leaf litter, beneath stones or debris outdoors. If access is available, the insects can thrive in the voids or openings beneath porches, in wall voids and crawlspaces. In more metropolitan areas, oriental roaches can be found in large numbers living in storm drains and sewers.

Oriental cockroaches are known for their preference of feeding on garbage, filth or material that has begun to decay. These cockroaches are very dependent upon water. While studies have shown that they can survive for up to a month without food, these insects can not survive for more than two weeks without water.

Management

orientalis often deposits oothecae in cracks and crevices that can be very difficult to treat with insecticides, or by the time the nymphs hatch from the oothecae the application is degraded or removed. Therefore new methods are being developed to manage the roach in combination with regular sprays and dusts. There has been an increased interest in recent years to use juvenile hormone analogues (JHAs) for the control of many insect pests. JHAs have a low vertebrate toxicity, a highly specific biological action and disrupt growth and reproduction in insects, which makes it a good candidate for use in domestic and public environments.

A chemical barrier around the perimeter of the home along with insecticides applied to specific locations inside will help control B. orientalis. However, rapid breakdown of the insecticides can occur because oriental cockroaches prefer to rest on damp surfaces. The following are some other tips that can help the management of B. orientalis in and around the home.

The outsides of doors, windows, pipe openings and dryer vents should be treated with a good residual spray.Any plumbing leaks should be fixed, and any moist spaces should be ventilated. Cracks in the structure should be caulked at ground level. Decaying leaves and organic matter should be removed away from windows and doors.Garbage cans should be kept out of moist habitats. Drain traps should be kept full or capped.