Welcome to the World of Cockroaches
INTRODUCTION
Cockroaches, since they have been around, have changed very little. Most species
are of tropical or subtropical origin. Although they are not social insects, they commonly
occur in groups. They will feed on practically anything of nutritive value.
Of the approximately 4,000 living species of cockroaches in the world, about 70 occur in the United States. Only a few of these cockroach species inhabit man's dwellings. The more common are the American, Australian, Brown, Brownbanded, German, Oriental, Pennsylvania wood, and the Smokybrown cockroaches. By far, the most common is the German cockroach.
Cockroaches are among the worst pests of house holds and commercial establishments. Not only is their mere presence a nuisance but they are known to be capable of carrying many common disease pathogens as well as causing allergic reactions in many people. The more common of such disease pathogens include bacteria in the genera Salmonella ( food poisoning), Staphylococcus, Streptococcus, Coliform, Bacillus, and Clostridium, the bacteria Escherchia coli (diarrhea) and Shigella dysenteriae (dysentery), the protozoan-caused parasitic toxoplasmosis, and hepatitis B antigen.
RECOGNITION
Oval in outline, body usually flattened, head partially or entirely concealed
beneath pronotal shield (expanded pronotum). Front wings leathery with veins, although
veins may be reduced. Antennae long and threadlike. Abdominal cerci usually long., not
forceps-like. Tarsi 5-segmented. Mouth parts chewing.
IDENTIFICATION
It is advisable to know the cockroach species being encountered because cockroaches
vary in their food preferences and living habits. For example, American cockroaches prefer
living in food-storage areas, basements, steam tunnels, and sewers, prefer fermenting
foods, and enter an account by being brought in, via sewers, or occasionally by
migrations. In contrast, Australian cockroaches, which are very similar in appearance,
prefer plants but otherwise occupy habitats similar to the American except for sewers,
prefer new plant shoots or starchy materials, and are usually brought into an account in
potted plants. Therefore, if drains (sewers) and outside areas are not inspected for
American cockroaches, or plants for Australian cockroaches, the chance of controlling or
eliminating the customer's cockroach problem is greatly reduced.
BIOLOGY
Cockroaches have simple metamorphosis: egg, nymph, adult. Nymphs and adults are
usually similar in appearance except for size and the typical addition of wings in the
adult of most species; all newly emerged cockroaches are white, but will assume their
typical coloration within a few hours as their cuticle hardens. They are gregarious, thus
all stages and instars are found together in their preferred harborages, except that they
tend to be size segregated by crack/crevice thickness. Domestic species are nocturnal or
active at night but will be out during when the infestation is very large and acceptable
harborages are filled to overflowing with cockroaches.
Females produce egg-containing ootheca (singular ootheca) or egg cases/capsules. Each ootheca may contain as few as 4 to as many as 50 eggs, depending on the species. The ootheca is usually dropped or glued to some surface in a sheltered situation near a food source within a couple of days following formation. However, the German cockroach carries it's ootheca until 24-48 hours before the eggs hatch and the nymphs emerge.
Parthenogensis or egg production without fertilization does occur in American, Brown, Brownbanded, German, and oriental cockroaches. Egg capsules produced this way usually fail to hatch or produce only a few nymphs.
Developmental time (egg to adult) is strongly influenced by temperature and humidity. It can be as short 53 days for the German cockroach to as long as about 2 years for the oriental cockroach. Both the developmental time and the preferred harborage areas reflect the tropical or subtropical origin of cockroaches. in general, a high temperature and a high relative humidity are preferred in harborage areas and will shorten developmental time.
Cockroaches spend about 75% of their time in crack and crevice harborages into which they can just squeeze. The most preferred harborages are those of the proper size that are located nearest food and water sources but which are warm and have a high relative humidity.