The German cockroach (Blattella germanica) is a small species of cockroach, measuring about 1/2" to 5/8" (1.3 cm to 1.6 cm) long. It is tan to light brown, and has two dark parallel streaks running from the head to the base of the wings. Although it does not have wings, it is very skilled at flight and is able to sustain flight.
The German cockroach is one of the most common and prominent household cockroaches in the world, and can be found throughout many human settlements in the world. In colder climates, it is found only near human habitats, since it is not very tolerant towards the cold. The German cockroach is originally from Asia, and is also very closely related to the Asian cockroach, to the extent that to the casual observer they appear nearly identical and may be mistaken for the other.
The German cockroach is very successful at establishing a niche in buildings, and is very hardy and resilient towards attempts to exterminate them. This is due to the fact they produce a large number of nymphs for each egg case, and that there is a short period between birth and sexual maturity. The mother also carries the egg case with her during the germination period, rather than depositing the egg case like other species, a practice which would leave them vulnerable in a human habitat against zealous attempts to wipe them out. The 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. The German cockroach, discounting the presence of pets, has few natural predators inside a human habitat.
The German cockroach eats a wide variety of items. They particularly like starch, sugary foods, grease and meats. The cockroach can be seen in the day, especially if there is a large population or if they have been disturbed; sightings are commonly reported in the daytime hours. However, they are nocturnal, and therefore most active at night.
The Australian cockroach (Periplaneta australasiae) is a large species of cockroach, winged, and growing to a length of 1 1/4"-1 3/8". It is brown in colour. It is very similar in appearance to the American cockroach and may be mistaken for it easily. However, it is a bit smaller than the American cockroach, has a yellow margin on the thorax, and yellow streaks at its sides as the wing base.
Despite its name, the Australian cockroach originated in Asia. It is very common in the southern United States and in tropical climates, and can be found in many locations throughout the world due to its travels via shipping and commerce between locations. It can be found in Florida, California, and other coastal states.
The insect can travel quickly, often darting out of sight when someone enters a room, and can fit into small cracks and under doors despite its fairly large size. It is known to be very mobile, it also has wings which allow it to be quite a capable flier.
It prefers warmer climates and is not cold tolerant, however, it may be able to survive indoors in colder climates. It does well in moist conditions but also can tolerate dry conditions as long as water is available. It often lives around the perimeter of buildings, and it is one of the most common species outdoors in Florida. It appears to prefer eating plants more than its relatives do, but can feed off a wide array of organic (including decaying) matter like most cockroaches, it is a scavenger.
It may comes indoors to look for food, and even to live, however, in warm weather it may move outdoors and enter buildings looking for food.
The American cockroach (Periplaneta americana) is a large species of cockroach, winged, and growing to a length of 1" to 1½" (2.5 cm to 4 cm). It is very common in the southern United States, and in tropical climates, and can be found in many locations throughout the world, due to its travels via shipping and commerce between locations. In the southern U.S., it is often called a Palmetto Bug or a Waterbug. Sightings have been reported in the northeast U.S., such as in New York City, and in southeast Canada, such as in Montreal, where it is mostly found near human habitations due to its lack of cold tolerance. The American cockroach can also be found near various ports throughout the world.
The insect is believed to have originated from Africa, but had become established in the southern U.S. by the time that it was given its name.
The insect can travel quickly, often darting out of sight when someone enters a room, and can fit into small cracks and under doors despite its fairly large size. It is known to be very mobile, and it also has wings which allow it to be quite a capable flier.
It prefers warmer climates and is not cold tolerant, however, it may survive indoors in colder climates. It does well in moist conditions but also can tolerate dry conditions as long as water is available.
The insect is often considered a pest since it invades living quarters for sanctuary and food
Hadlington, P. and Marsden, C. (1999) Common Household Pests: A Homeowners Guide to Detection and Control, UNSW Press.