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Periplaneta americana (American cockroach)

Life > Eukaryotes > Opisthokonta > Metazoa (animals) > Bilateria > Ecdysozoa > Panarthropoda > Tritocerebra > Phylum: Arthopoda > Mandibulata > Atelocerata > Panhexapoda > Hexapoda > Insecta (insects) > Dicondyla > Pterygota > Metapterygota > Neoptera > Polyneoptera > Dictyoptera (cockroaches, mantises and termites) > Family: Blattidae

Periplaneta americana (American cockroach), in Cape Town home. [photos H.G. Robertson, Iziko ]

Distribution and habitat

Despite its name, the American cockroach is not native to America but rather West Africa. It has been introduced to just about all parts of the world, thriving in moist, warm places, usually in association with human habitation. 

It is the most common of the cockroaches found in people's homes in coastal areas of southern Africa (e.g. in Cape Town) and is also found in most other urban areas in the region. It likes warm, moist cavities such as those found behind paneling beneath the kitchen sink. It is also found in large numbers in sewers and some homes are particularly vulnerable to repeated infestation by cockroaches from nearby sewerage systems (particularly old ones that have moist spaces where they can live).   

 Life cycle

  • Like almost all cockroaches, eggs are laid in an egg case called an ootheca. Each egg case contains about 14 eggs. The egg case is usually hidden in a crevice and egg development lasts 1-2 months. A single female can produce about 12-24 egg cases over the warm summer months.
  • The nymphs that hatch from the eggs undergo 13 moults over a period of 6-12 months before they reach maturity.
  • Adults are about 30 mm long and often live more than a year, so with the younger life stages included, the life span can total nearly two years.

Natural enemies

 
Evania appendigaster. [photo S. van Noort ]  

The wasp Evania appendigaster parasitises the egg cases of the American cockroach. In cockroach prone areas, this wasp can often be seen flying and strutting around on the window sill. It is black with a funny, small triangular abdomen. It does not sting, it is not dangerous, and you should regard it as friend, not foe.

Importance

  • As you can imagine, having a cockroach wandering out of a sewer into your kitchen and on to food, can't be good for hygiene. Thus these cockroaches can contaminate exposed food with bacteria.

  • American cockroaches have a very strong, distinctive smell and can cause allergic reactions.

  • Some people get quite freaked out by these insects as they are large, fast, spikey, smelly and a health hazard.

Control

  • Sanitation. These cockroaches feed mainly at night. If there are food remains, dirty plates, crumbs on the floor or scraps left exposed in your kitchen overnight you are basically providing them with an ongoing food supply that is going to swell their numbers. Clean your kitchen each evening before going to bed. It's an idea to put the plug in the sink overnight as this will stop them entering the kitchen through the drain.

  • Design of your  home. American cockroaches can be difficult to control adequately if they are living in cavities that cannot be removed. For instance, kitchen cupboards are often constructed with a back panel so that there is a cavity between the panel and the wall. If such a cavity is not sealed, cockroaches are likely to find it and breed in it, particularly if the wall is damp or the panel is beneath a sink or basin.   Cockroaches like hiding under fridges and stoves or in horizontal or vertical cavities at ground level.

  • Insecticides. Spraying a surface spray type of insecticide in cavities where cockroaches reside and along skirtings on the floor can be effective in killing some.

  • Cockroach traps. These consist of a sticky surface on which the cockroaches get stuck. Put them out in places where you see a lot of cockroaches.

Links

References

  • Bell, W. J., and K. G. Adiyodi. 1981. The American Cockroach. Chapman & Hall, New York.

  Text by Hamish G. Robertson  


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