170 NATURAL HISTORY OF ARTHROPODS. 



they cause. The Blattidas have received all sorts of popular names, but they are best 

 known as " black-beetles " and cockroaches. Their colors, as a rule, are various shades 

 of dull brown and black, which agree well with their nocturnal habits and the dark 

 haunts they frequent. The body of most species is comparatively large, broad, and 

 flat, and is covered by a very flexible, leathery integument. In some genera the head 

 is almost, while in others it is entirely, concealed beneath the prothorax. The antennae 

 are very long and thread-like ; the feet and limbs are strong and spined, and admirably 

 adapted for running as well as for crawling into narrow cracks and crevices a habit 

 belonging in a greater or less degree to all the species of the family. During the day- 

 time we see very little of these insects, and become surprised by their sudden appear- 

 ance at nightfall. This, however, is owing to their nocturnal habits and their trait of 

 hiding themselves away, in which they are materially aided by their compressible 

 skins and the flatness of their bodies, which allow them to squeeze into very nar- 

 row places. 



The species of Blattida?, on account of their mode of life, are the most widely 

 distributed of all Orthoptera, and are exceedingly common in some localities. This is 

 especially the case in seaport towns, and on board of ocean steamers, where, favored 

 by the warmth from the engines and the prevailing dampness, they thrive and multiply 

 amazingly. It is therefore an absolute necessity that all goods to be transported from 

 one country to another be well packed in order to be secure against injury from these 

 insects. They have become generally distributed over the entire face of the globe 

 wherever navigation has extended, and have, in fact, very generally followed man. 

 We may rejoice that these cosmopolitan species are so few when we reflect upon the 

 great amount of injury caused by each. Besides these wide-spread and generally-known 

 species, there are numerous other representatives of the family that we find in the 

 woods under bark of trees, in old and rotten logs, and under stones and all sorts of 

 debris. This family is most numerous within the tropics, where many of the species 

 are of great size, but do not differ greatly in habit from those living in our woods. 



FIG. 246. Egg cases of a cockroach, Periplaneta oriental is : natural size above. 



The principal characters used in the classification of the Blattidas are the form of 

 the prothorax, the limbs, the terminal plate of the abdomen, and the cerci. The rela- 

 tive position of the head also aids materially, while the presence or abbreviation of 

 the wings is likewise significant. The eggs of cockroaches are all laid at once, and 

 encased in a purse-like pod, the form of which varies among the different genera. 

 The operation of egg-laying with these insects, it is claimed, requires many days. The 

 ootheca, as these egg-cases are called, contains a double row of eggs that are placed 

 upon either side of a slit or opening which extends the entire length of the pod. The 

 color of this ootheca when first protruded from the body is almost white, but with 

 time it generally assumes the color of the species to which it belongs. The female 



