German Cockroaches - Biology & Control

German Cockroach (Blattella germanica)
Rats

Origins and distribution

Found worldwide and throughout the UK. It has been suggested that it was introduced to the UK around the time of the Crimean War.

Characteristics

German cockroaches are about 12 – 15 mm in length and are a mid-brown (beige) colour with 2 dark brown strips on the pronotum. They have long filiform antennae and long spiny legs, which enable them to climb even on smooth surfaces.

Breeding

Egg cases (ootheca) contain about 30 – 40 eggs, which are carried by the female on the rear of her abdomen for 2 – 4 weeks and deposited just before hatching.  Nymphs go through 6 – 7 moulting stages before reaching the adult stage, this takes about 3 – 6 months depending upon temperature and humidity. Adults are winged but cannot fly in the UK and live for an average of 6 months.

Habits

Primarily nocturnal and prefer warm humid conditions in buildings. They can infest the motor areas of machinery and refrigeration units, electrical equipment and switches, drinks and vending machines, inside the electrical compartments of microwave and oven units, inside the outer panels of washing machines, cracks and crevices of walls or furniture, even in door hinges and curtain folds.

Signs of activity

  • Black faecal marks or spotting around the harbourage area.
  • Shed moulted skins.
  • Empty ootheca (egg cases).
  • Particular smell associated with large numbers.

Importance

German cockroaches can become serious pests in heated buildings and can be found in restaurants, grocery stores, bakeries as well as domestic properties. If left untreated infestations can really take hold and spread within a building where the insects harbour within the building structure if conditions allow. They are known to carry various human disease organisms.

How we control German Cockroaches

German cockroaches are generally controlled by the placement of gel bait, which acts as a stomach poison which starts killing the insects within hours after ingestion. The bait formulation also has the ability to disrupt the eggs if being carried by the female at the time of poisoning. German Cockroaches are scavengers and cannibalistic in nature and this habit of scavenging on another dead German cockroach that has been poisoned acts as a domino effect with secondary poisoning occurring.

The gel bait is applied to various cracks, crevices, around pipes, inside electrical conduit, around fridge and other electrical motors and where they harbour along with insect monitors (glue traps) that attract them in to be caught. This helps as a monitoring tool and establishing numbers, areas of activity and when riddance has been achieved. Depending upon the environment and legislation requirements regular routine maintenance or service visits may be necessary. We can tailor our service to customer needs.

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