Cockroaches

Pest Name: German cockroach - Blattella germanica

Markings: Light beige, with two dark stripes on the pronotum behind the head.

Location: Numerous locations usually close to food and water.

Detection: Visual sightings of adults and nymphs.  Odour.  Faecal spotting.  Egg cases.

General Information: Size - 11-16 mm overall body length.

The German cockroach, also known as the steam fly (due to it's liking of hot environments) is thought to have originated in North East Africa, but now can be found virtually all parts of the world. 

It prefers warm moist conditions (25-30oC) and has consequently become a common pest of heated buildings, notably in kitchens, larders and restaurants; it is very prevalent in the galleys, storerooms and accommodation of modern ships.  In warmer climates, such as the southern States of America, the German cockroach occurs outdoors but this is rare in Britain.

Biology: The adult German cockroach is small (11-16 mm) and beige coloured with two distinct dark parallel bands running the length of the pronotum, behind the head.  The wings are as long as the body in the male and almost as long in the female.  It is generally more active than the Oriental cockroach and more readily seen during the day.  The egg case or ootheca is 8 mm long and is a chestnut brown colour.  Look carefully and you will see that it has about 18 segments.  The female carries the egg case until the eggs hatch.  Oothecae are produced at about 3 - 4 week intervals and contain 35 - 40 eggs.  German cockroaches have an incomplete metamorphosis (egg, nymph, adult).  There are usually 6 nymphal stages, with development to the adult taking 6 - 7 weeks at 30oC.  The adult life span is 4 - 5 months.

Reasons for Control:

The German cockroach is now known as a major pest of buildings, particularly in warmer climates or where central heating is present.  It is the second most important cockroach pest in Britain.  Because of its habits and feeding sites, it is a potential carrier of pathogenic bacteria when associated with food.  People also find their presence and odour repulsive.  A recent study in the USA suggests that nearly one fifth of the population is allergic to cockroaches.