COCKROACH', the name applied to members of the Blat tidae, a family of orthopterous insects, with flattened bodies, long thread-like antennae and shining leathery integument. They are eminently tropical but certain species have become widely dis seminated through commerce and are now cosmopolitan. Cock roaches are nocturnal in habit, hiding themselves during the day. The domestic species are omnivorous but are especially addicted to starchy or sweetened matter of various kinds : they also attack provisions, paper, clothing, books, shoes, bones, etc., and dead insects. As a rule they injure and soil far more than they consume, and most species emit a disagreeable odour.
The common or oriental cockroach (Blatta orientalis) has the wings shortened in the male and vestigial in the female. The eggs, 16 in number, are laid in a horny capsule or ootheca which is carried for some time, projecting from the body of the female, until it is deposited in some crevice. The capsule ultimately splits and the young insects emerge. They are said to undergo six moults and require at least a year before becoming mature, but little is definitely known on this point. The American cockroach (Peri planeta americana) is a much larger insect with fully developed wings in both sexes and in Britain it is found in warehouses and hothouses, etc. It is sometimes found in conjunction with the smaller or so-called German cockroach (Blattella gerrnanica). These three species are also widely distributed in North America along with other introduced kinds. About 1,200 species of cock roaches are known and of these only two small species, belonging to the genus Ectobius, are true natives of Britain and live out of doors. Although cockroaches are usually sombrely coloured some tropical species exhibit elegance of form and beauty of coloration. The delicate green Panchlora sometimes occur in various parts of Britain, being accidentally imported with fruit, etc.
Cockroaches can be readily destroyed by means of special traps baited with molasses; dusting the places they frequent with either sodium fluoride or powdered borax is also effective. Although these insects are usually viewed with disgust they are not devoid of interest. They rank as the most primitive of all winged insects and are among the oldest of all the fossil forms of those animals. Their generalized structure and large size render them convenient objects for laboratory dissection and they are universally adopted as the most suitable type for commencing the scientific study of insects.
See Miall and Denny, The Structure and Life History of the Cock roach (1887) ; Herrick, Insects injurious to the Household (1914) ; Lucas, British Orthoptera (192o) ; Laing, The Cockroach (British Mus. 1921) . D. I.)