T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network


Cockroach (German) Blattella germanica

Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Blattodea
Family: Ectobiidae
Genus: Blattella
Species: Blattella germanica
Binomial name: Blattella germanica
Common name: German cockroach

Blattella germanica is a small, cosmopolitan species of cockroach. Recent evidence suggests that it originated in Southeast Asia but is now a household pest on all continents except Antarctica, and on many major islands as well. Blattella germanica occurs widely in human buildings but is particularly associated with restaurants, food processing facilities, hotels, and institutional establishments such as nursing homes. In cold climates, they occur only near human dwellings, because they cannot survive severe cold.

Blattella germanica adults are 13-16 mm long. They can fit through an opening as small as 9.5 mm in width. They vary in colour from tan to almost black, and it has two dark, roughly parallel, streaks on the pronotum running anteroposteriorly from behind the head to the base of the wings. Although Blattella germanica has wings, it can barely fly, although it may glide when disturbed. It is typically nocturnal though it may be occasionally seen during the day. When excited or frightened, the species emits an unpleasant odour.

Blattella germanica are omnivorous scavengers. They are attracted particularly to meats, starches, sugars, and fatty foods. Where a shortage of foodstuffs exists, they may eat household items such as soap, glue, and toothpaste. In famine conditions, they turn cannibalistic, chewing at each other's wings and legs.
They reproduce faster than any other residential cockroach, growing from egg to reproductive adult in approximately 50 – 60 days. Once fertilised, a female German cockroach develops an ootheca in her abdomen. The abdomen swells as her eggs develop until the translucent tip of the ootheca begins to protrude from the end of her abdomen, and by that time the eggs inside are full sized, approximately 6.5 mm long with 16 segments. The ootheca, at first translucent, soon turns white and then within a few hours it turns pink, progressively darkening until, some 48 hours later, it attains the dark red-brown of the shell of a chestnut. The ootheca has a keel-like ridge along the line where the young emerge, and curls slightly towards that edge as it completes its maturation. Females carry the ootheca for up to a month, dropping it just before the eggs hatch. A small percentage of the nymphs may hatch while the ootheca is still attached to the female, but the majority emerge some 24 hours after it has detached from the female's body. The newly hatched 3mm-long black nymphs then progress through six or seven instars before becoming sexually mature, but ecdysis is such a hazardous process that nearly half the nymphs die of natural causes before reaching adulthood. Moulted skins and dead nymphs are soon eaten by living nymphs present at the time of moulting. There can be six generations per year.
Studies suggest Blattella germanica acts as a reservoir and potential vector of some bacterial pathogens. Some people develop severe allergies to cockroach parts, faeces, and oils.

 



An adult with nymphs


A photo of a female Blatella_germanica with ootheca attached.
 


A video on the German cockroach.

Thanks to Wikipedia for text and information: https://creativecommons.org/licenses/by-sa/3.0