Cockroaches are important nuisance pests often associated with urban environments. They are known to humans since ancient times and are thought to have evolved during the Silurian Period, some 350 million years ago. Cockroaches were generally classified in the order Blattodea, but recent molecular phylogenetic studies suggest that they are monophyletic with termites with which they share a common ancestor and thus could be classified within the termite order Isoptera (reference).
Cockroaches are a source of nuisance for human beings. This is primarily because cockroaches are often found filthy environments such toilets and other unhealthy places, and their presence in home and workplaces may imply a higher risk of contamination. Although cockroaches do not vector any disease to human or animal, they can mechanically transport and transmit pathogens to humans.
Cockroaches are omnivorous, meaning that they feed on almost anything they come across. They have chewing mouthparts that allow them to few on any organic material. Just like termites cockroaches have gut symbionts which help them in the digestion of food.
Classification and Importance of Cockroaches in the World
Globally, there are more than 4000 described species of cockroaches. Although most of these cockroach species live in the wild, few species (around 20) (reference) have managed to adapt to living with humans. Those human-associated cockroaches are omnivorous and feed on any organic material they come across. (reference).
In the United States, it is estimated that there are 70 species of cockroach and 24 of them where introduced from another part of the world (reference). Five families of Cockroach have generally been considered as pests including, Blattelidae, Blaberidae, Blattidae, Cryptocercidae, and Polyphagidae but the first three families are most of the concern in the United States although their pest status varies according to the species (reference).
Mouthparts of Cockroaches
The mouthparts of cockroaches are biting and chewing type. Both nymph and adults have similar mouthparts, typically with strongly toothed mandibles. and well-developed labial and maxillary palps.
Morphology of cockroaches
Adult cockroaches have tow pair wings. The front wing or tegmina are hardened, translucent. The veins are clearly visible and well defined. Cockroach genitalia is often used for distinction between males and females. Cockroach has saltatorial legs adapted to running fast. The ability to fly depend on the species.
The species of cockroaches often found in urban environments
According to Richard , there are 11 species of cockroaches that commonly occur in the United States. These species include:
- The German cockroach (Blattella germanica)
- The Oriental cockroach ( Blatta orientalis)
- The American cockroach (Periplaneta americana)
- The Australian cockroach (Periplaneta australasiae)
- The brown-banded cockroach (Supella longipalpa)
How to know if there are cockroaches in your house?
The clear sign of cockroaches infestation is the presence of their egg cases ( also know as oothecae). Now how to recognize a cockroach egg case? This may depend on the species but in general the egg case is a light brown, purse-shaped capsule.
These eggs cases may be found at different places inside the house. The most obvious sign of cockroach infestation is actually seeing them. Most cockroaches species are active only during night time in the dark. It is very common to find them in and around toilets during night time. They may also be found in and under the sink at dark. During the day cockroaches are rarely seen.
Bio-ecology of cockroaches
Problems associated with cockroaches
Cockroach Prevention and Control
Chemical control is often the solution to cockroach infestation. However this can difficult to achieve due to the bio-ecology of cockroach, especially the domestic and peridomestic species that are only active during night time. Pest control companies often rely on bait to poisonous bait that lure and kill a large colony of cockroaches. Pesticides used for pest control include organosphosphates, carbamates and to some extent pyrethroid insecticides. You can read this article that I wrote about how to kill a cockroach by yourself.