The German Cockroach is one of the smallest cockroaches (13-16mm) that infest human habitats but is the most successful and widespread of all the species that live around humans. They are pale brown in colour and have two dark stripes on the pronotum. The male German cockroach is a lighter brown than the female and has a more slender abdomen than the female who has a broader posterior. Both the male and female have wings but neither fly. The nymph also has the clearly seen stripes that extend right down the back of the roach.
The German cockroach is a prolific breeder. The female will carry the egg cases right up till hatching (within 1-2 days), each egg case will contain between 30-40 eggs. The average incubation period is 28 days which is extremely fast however the range is between 14-215 days, the incubation taking longer or shorter given conditions. Once the eggs hatch the nymph stage will begin, it proceeds very rapidly with the male adult developing quicker. Nymph to adult development is 32-40 days but is dependent on favourable conditions. The nymph will go through 6-7 moults (instars) with each moulting progressively more like an adult. The average adult will live a maximum of 200 days.
Incredibly, if an injury occurs to a nymph (eg loses a leg or a developing wing) the nymph will undergo additional moults and actually repair the damage – and actually grow a new limb!
The German cockroach prefers warm and moist environments with ample food sources. Most German Cockroach infestations occur in kitchens or where food is prepared or handled. This can include kitchen cupboards, pantries, storerooms, fridge components including seals, dishwashers, bathrooms, particularly under sinks. A sign of a massive infestation is where this cockroach is seen in numbers in areas outside of the aforementioned areas. A home can literally support populations in the 10’s of thousands, these levels being common in commercial situations including cafe’s, restaurants, factories (food prep or manufacture) warehouses, markets, hotels and pubs, canteens, mobile food vans and take away shops.
Due to its small size, you will find hundreds of German Cockroaches jammed and crammed into every crevice where infestation occurs. Some bad infestations have included a commercial fridge against a wall with the entire shadow of the refrigerator being covered in a thick mat of German Cockroaches. They have been known to get inside vegetables such as pumpkins and hollow them out supporting thousands of cockroaches.
This cockroach is usually transported from one location to another – from cardboard boxes to handbags, the German cockroach will hitch a ride wherever it can. Once established it will breed prolifically and create a massive population in a short period of time. Its faecal smears with aggregation pheromone mean this cockroach is extremely social and gathers in massive groups.
The German cockroach will eat anything organic. They will feed on both protein and carbohydrate-based foods and at particular times of the year may prefer either. The German Cockroach will find food in any situation and no matter how clean an environment is, once infested only professional eradication can remove the problem.