( Latin: Sub-order Blattodea)
Cockroaches are also regarded as primitive insects, and fossil species known from the Carboniferous period some 250 million years ago are very like those known today.
There are about 3,500 different species of cockroaches and the vast majority of these live in the open and almost never come in contact with man.
A few small species are native to northern Europe (see p. 201), but the majority are tropical.
The cockroaches found indoors in temperate regions have been introduced from the tropics during the last 200 years, and most of them are completely dependent upon heated buildings.