Order Blattodea (Cockroaches)
Introduction
Cockroaches are small to large (3 – 50 mm) insects that have a pronotum covering the head and a distinctive oval body shape. Cockroaches have biting/chewing mouthparts, generally eat a wide range of vegetable and animal matter debris. Most species have two pairs of wings, although these may be reduced or absent adults of some species. Most cockroaches are tropical and want nothing to do with humans whatsoever. However, there are a few species of cockroaches that really appreciate the wonderful homes we make for them and all the food we give them. At least that's how they see it.
Life Cycle
Cockroaches have simple metamorphosis and may pass through 5 – 13 instars before becoming adults. Thus, the adults and immatures are found in the same places, doing the same things, and feeding on the same things. Eggs are contained in bean-like capsules called oothecae that females may carry, drop, or glue to a structure. The immatures resemble the adults, but wings are not fully developed and they are smaller. Immatures grow by molting and may require from 2 months to 3 years to fully mature, depending on species and environment.
How to Photograph Cockroaches
Many cockroaches will run away at the approach of a photographer, but if care is taken some will allow a close approach. Specimens may need to be captured and cooled/stunned/killed before they can be photographed.
How to Collect and Preserve Cockroaches
Hand collection is generally the best way to collect cockroaches.
For short term preservation cockroaches can be killed in a killing jar or preserved alcohol. For long term preservation adult cockroaches should be pinned and immatures should be preserved in alcohol.
How Cockroaches Affect Humans
Cockroaches are not picky eaters and will feed on plant and animal products, meat, grease, starchy foods, sweets, baked goods, unprotected kitchen goods, leather, wallpaper paste, and book bindings.
Cockroaches enter buildings to escape cold, hot, dry, or wet conditions, and infest even the most sanitary buildings. Cockroaches prefer warm, dark, humid shelters around sinks, in cracks around cupboards and cabinets, where pipes or wiring pass through walls, behind windows or door frames, upholstered furniture, bathrooms, etc. They are nocturnal, appearing during daylight only when disturbed or in high numbers. They enter buildings through boxes, cartons, furniture, dried pet food, loose fitting doors/windows, holes where electric lines or water pipes pass through walls, firewood, and sewer lines.
Cockroaches have secretions that give off an odor and can even corrode metal. Cockroaches may damage electronic equipment and have caused electrical fires. For many people they are a source of anxiety and stress. Some people may be affected by cockroach allergens, especially in areas with massive infestations. Cockroaches carry disease organisms on their bodies including bacteria, fungi, worms (such as hookworms and pinworms), protozoa, and viruses.
Cockroaches have been used in research, as fish bait, for chicken feed, and as pets. Cockroaches not associated with humans may live in leaf litter, sand, tree tops, ant nests, etc.
Common Pest Cockroaches
German Cockroach
The German cockroach, Blattella germanica (Linnaeus), has been called the "Croton bug". It was introduced into the United States from Europe and is originally from Asia or Africa. The German cockroach is pale brown and 13 - 16 mm (1/2 - 5/8 in) long. The head shield or pronotum has two dark stripes that run lengthwise. The wings of both sexes are as long as the body. Nymphs are wingless and darker in color (nearly black). The have a single light stripe running down the middle of the back. This is the most common roach in Louisiana, and it prefers kitchens and bathrooms. The female may have 48 eggs/case and carries the egg case. Nymphs hatch in 1 week and become adults in 6-8 weeks. Their life cycle may be completed in 2 months.
Smokybrown Cockroach
The smokybrown cockroach, Periplaneta fulginosa (Serville) is uniformly dark and about 3.2 cm (1.25) inches in length as an adult. The wings cover abdomen, and this is the second most important roach in Louisiana. The head shield or pronotum is a solid dark color. They prefer to be outdoors in humid areas with lots of organic matter. There are about 24 eggs/case, and the case may be attached to a structure or dropped. The life cycle is from 10-16 months.
American Cockroach
The American cockroach, Periplaneta americana (Linnaeus), has also been called the "waterbug" and the "Bombay canary". It is originally from Africa. This roach is reddish – brown and has a yellow border on the head shield or pronotum. The adult is 3.8 cm (1.5 in) long. The wings of the male extend slightly beyond the tip of abdomen. The wings of the female are about the same length as the abdomen. Young nymphs are grayish-brown becoming more reddish-brown with age. These roaches generally drop the egg case and have about 15 eggs/case. The life cycle is from 12-16 months. They prefer dark, moist sites in kitchens, bathrooms, basements, steam tunnels, sewers, and crawl spaces.
Brownbanded Cockroach
The brownbanded cockroach, Supella longipalpa (Serville), is from 13 - 16 mm (1/2 - 5/8 in) long as an adult. These roaches are light gold to glossy dark brown and have transverse yellow bands running across the base of the wings and abdomen. The wings of the male cover the abdomen; but, the wings of the female are shorter than the abdomen. The yellow bands are more pronounced on the nymphs. There are about 16 eggs/case, and the female glues the egg case to objects. They prefer starchy food and need less humidity than other roaches. They are found on ceilings, in light switches, in cabinets, in closets, and on furniture.
Oriental Cockroach
The Oriental cockroach, Blatta orientalis (Linnaeus), has been called the "waterbug," "black beetle" (a misnomer, cockroaches are not beetles), and "shad roach". It was introduced into the United States from Europe and is originally from Asia or Africa. It is dark brown to black in color. The female is 1 ¼ inches long, and the male is 1 inch long. The wings of the male cover ¾ of the abdomen; but the female has small rudimentary wings. The nymphs resemble adults. Egg cases may contain about 16 eggs. They enter buildings in dry or cold weather and prefer high moisture areas such as sewers, drains, and damp basements. They like to be at ground or below ground level.
Summary and References
Five families and ~67 species of Blattodea are recorded from North American North of Mexico. Helfer (1987)[1], Mallis (1997)[2], and Triplehorn and Johnson (2005)[3] are good general references for information about this order.
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Print References
- ↑ Helfer, J. R. 1987. How to know the grasshoppers, crickets, cockroaches, and their allies. Dover Publications, New York, NY. 363 pp.
- ↑ Mallis, A. (ed.). 1997. Handbook of pest control: the behavior, life history, and control of household pests. 8th ed. Mallis Handbook & Technical Training CO. Cleveland, OH. 1456 p.
- ↑ Triplehorn, C. A., and N. F. Johnson (eds). 2005. Borror and Delong’s introduction to the study of insects. 7th Edition. Brooks/Cole Publishing, Kentucky, U.S.A. 868 pp.
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