The principal diseases transmitted by cockroaches are forms of gastroenteritis (food poisoning, dysentery, diarrhoea and other illnesses), they are carried on the legs and bodies of the cockroach and are deposited on food and utensils as they forage. Cockroach excrement and cast skins also contain a number of allergens to which many people exhibit allergic responses, such as skin rashes, watery eyes and sneezing, congestion of nasal passages, and asthma.
Cockroaches produce odorous secretions that can affect the flavour of various foods and in stances where populations are high, these secretions may result in a characteristic odour in the general area of the infestation. Disease producing organisms such as bacteria, protozoans, and viruses have been found on cockroach bodies.
The key to cockroach management is thorough inspection. A cockroach survey (trapping) is sometimes necessary to determine the extent of an infestation, as even a thorough inspection will not reveal all cockroach harbourages or foraging areas.
Surveys involve placing sticky traps at strategic locations within the building. Whenever possible, place survey traps either against a wall or in a corner of the floor, a shelf, or a drawer, or under equipment and counters.
Most commercially available traps come complete with bait to encourage cockroaches to enter. Weekend trapping with sufficient number of trapping sites (ten or more) usually provides enough information to determine effective control plan.
Adult German cockroaches are 1/2 to 5/8 inch long and tan to light brown. Although they have fully developed wings, they do not fly. Nymphs are similar in appearance to adults except that they are smaller and lack wings. The German cockroach is best identified by its small size and by two dark parallel lines running from the back of the head to the wings.
It is usually found in kitchens (near dishwashers, stoves, and sinks) and in bathrooms of premises. German cockroaches usually prefer a moist environment with a relatively high degree of warmth. The insects are mostly scavengers and will feed on a wide variety of foods. They are especially fond of starches, sweets, grease, and meat products. In many locations, garbage is a principal food source.
As with other species, German cockroaches are mostly active at night, when they forage for food, water, and mates. During the day they hide in cracks and crevices and other dark sites that provide a warm and humid environment. They may be seen during the daytime, particularly if a heavy population is present or if there is some other stress, such as a lack of food or water or an application of pesticides.
German cockroaches produce a larger number of eggs per capsule, they undergo the shortest time from hatching until sexual maturity, resulting in a rapid population growth. A greater number of nymphs hatch successfully because the female carries the egg capsule during the entire time the embryos are developing within the eggs. Most importantly, German cockroaches are smaller than most other cockroaches and can conceal themselves in many places inaccessible to individuals of the larger species.
German cockroaches undergo three distinct life phases: egg, nymph and adult. German cockroaches breed continually. In a lifetime, a female cockroach is capable of producing almost 400 eggs. Populations grow quickly in optimal conditions. A typical thriving population is comprised of 75 percent nymphs and 25 percent adult roaches. German cockroaches begin life as eggs within an egg casing known as an ootheca.
The oothecae (capsule)contain approximately 35 eggs and are brown in colour. Oothecae are approximately 7 mm long and 2 mm wide. They are very resilient and can survive harsh conditions. Female German cockroaches carry the oothecae attached to their abdomens until about two days prior to hatching and then deposit them in a protected location. Oothecae may be seen protruding from the abdomens of German cockroach females. Nymphs emerge from the oothecae as tiny insects. They gradually darken into dark brown or black cockroaches with parallel lines visible upon the pronotum. German cockroach nymphs are wingless and incapable of reproduction. Nymphs molt six to seven times and can develop completely within 100 days under optimal conditions. The adult stage begins with the last successful molting . At this point, German cockroaches are approximately 15 mm in length and are winged. Adult German cockroaches are nocturnal insects that hide during the day and scavenge at night.
Shiny black to a dark reddish brown colour, oriental cockroaches are a pest invader that most frequently gains entry beneath the thresholds of doors, through open doors or gaps beneath siding, even following utility lines, pipes, open drains or sewers into a structure or home. The adults of the oriental cockroach are very different in appearance. The smaller adult male oriental cockroaches, reaching only a length of 25 mm, can be identified by the presence of three-quarter length wings, leaving the last few abdominal segments exposed. The larger adult female oriental roaches, reaching a length of 32 mm, on the other hand, lack wings altogether, having only large wing pads that cover the first couple of segments of the body. Neither the male nor female is capable of flight.
BEHAVIOUR, DIET & HABITS
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 cannot survive for more than two weeks without water.
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.
SIGNS OF AN ORIENTAL COCKROACH INFESTATION
During the warmer months, it is not uncommon to find oriental roaches outside around landscaping beds, congregating beneath moist gutters, or even scurrying out from storm drains and sewer grates at night. Mostly active at night, they can be found during the day in areas and rooms that are kept primarily moist, dark and undisturbed. Odour: in areas where large populations of oriental cockroaches are present, a musty odour can be detected. This odour is a result of chemicals that are secreted by the insects that are used to communicate within the population.