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The German cockroach (Blattella germanica) is a small species of cockroach, measuring about 1.3 to 1.6 cm (0.51 to 0.63 in) long; however, larger individuals have been recorded. It can be tan through brown to almost black, and has two dark parallel streaks running from the head to the base of the wings. Although it has wings, it is unable to sustain flight. Found throughout many human settlements. These insects are particularly associated with restaurants, food processing facilities, hotels, and nursing homes. In colder climates, they are found only near human habitats, since they are not very tolerant to cold. However, German cockroaches have been found as far north as Alert, Nunavut, and as far south as southern Patagonia. The German cockroach is originally from Africa. It is very closely related to the Asian cockroach, and to the casual observer they appear nearly identical and may be mistaken for each other. This cockroach can be seen in the day occasionally, especially if the population is large or they have been disturbed. However, sightings are most commonly reported in the evening hours, as they are most active at night. This type of cockroach can emit an unpleasant odor when excited or frightened.
The German is very successful at establishing an ecological niche in buildings, and is very hardy and resilient against attempts at pest control. This is because of the large number of nymphs produced from each egg case, the short period between birth and sexual maturity, and their ability to easily hide due to their small size. The mother also carries the egg case (ootheca) with her during the germination period, rather than depositing it like other species, a practice which would leave them vulnerable in a human habitat to zealous attempts to wipe them out. This cockroach is also smaller than many other species, so it can more easily hide and fit into very small cracks and crevices to evade humans. That is also the main reason they can most effectively be controlled with bait in cracks and crevices near harborages.  These pest control methods must kill 95% of the overall population to be effective in a property due to the fast reproductive cycles. Gel products, such as Advion and max force, are very effective against cockroaches  The German cockroach, discounting the presence of pets, has few natural predators inside a human habitat. Its thigmotactic nature compounds the difficulty of pest control treatment. The immature cockroaches will live off excretions and moults from the adult cockroaches, so can remain hidden away from most surface treatments.
As a consequence of pest control using sweet poison baits, German cockroaches that experience glucose as bitter are becoming more common, resulting in refusal to eat the baits. As a trade-off for this sugar aversion, these cockroaches take longer to grow and reproduce.
The German cockroach is omnivorous and a scavenger. They particularly like starch, sugary foods, grease and meats. In certain situations where there is a shortage of foodstuffs, they may eat household items such as soap, glue and toothpaste or they may even turn cannibalistic, often chewing on the wings and legs of each other.
Comparison of three common cockroaches
|Cockroach||German cockroach||Oriental cockroach||American cockroach|
|Size||12 to 15 mm (1.2 to 1.5 cm)||25 to 30 mm (2.5 to 3.0 cm)||28 to 43 mm (2.8 to 4.3 cm)|
|Habitat||Heated buildings, optimum 32 °C (90 °F)||20 to 29 °C (68 to 84 °F)||Same as German|
|Nymphal development time||6 to 12 weeks||6 to 12 months||4 to 15 months|
|Lifespan||6 to 9 months||1.0 to 1.5 years||1.0 to 1.5 years|
|Able to fly||No||No||Yes|
- Blattellaquinone, a sex pheromone of the German cockroach
- The insects and arachnids of Canada, part 14, The Grasshoppers, Crickets, and related insects of Canada and adjacent region
- Faúndez, E. I. & M. A. Carvajal. 2011. Blattella germanica (Linnaeus, 1767) (Insecta: Blattaria) en la Región de Magallanes. Boletín de Biodiversidad de Chile, 5: 50-55.
- Amalgamated Pest Control
- Rose Pest Control
- Federal Pest Control
- Wada-Katsumata, A.; Silverman, J.; Schal, C. (2013). "Changes in Taste Neurons Support the Emergence of an Adaptive Behavior in Cockroaches". Science 340 (6135): 972. doi:10.1126/science.1234854. (summary at BBC News)
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