These Orthoptera have a flat broad body, the thorax very much developed, the antennæ very long, and the legs thin but strong, which enable them to run with remarkable quickness. They diffuse around them a sickening odour, which often hangs about objects they have touched. Aristophanes, the Greek comic poet, mentions this peculiarity in his comedy of "The Peace." They come out mostly at night, and hide themselves during the day. They are the most cosmopolitan of all insects. Carried over in ships, they perpetuate everywhere, just like weeds! Persian powder, composed of pulverised pyrethra, is an excellent means to employ for their destruction.
Most of the species of cockroaches are black or brownish. Two among them, the Blatta Germanica and the Blatta Laponica, which are to be met with in the woods round about Paris, have domesticated themselves in dwellings of the northern countries. They are a quarter of an inch in length. The Russians pretend that the former was imported from Prussia by their army, on its return from Germany, after the Seven Years' War (1756-1762). Till this period it was unknown at St. Petersburg, where now-a-days it is met with in great numbers. It lives in houses, and eats pretty nearly everything, but prefers white bread to flour and meat. The Blatta Laponica devours the smoked fish prepared for the winter.
The German naturalist, Hummel, made some interesting obser vations on the development and habits of the very prolific Blatta Germanica. It lays its eggs in a silky capsule, which is in the form of a bean, with two valves in the interior. This is drawn about for some time appended to the extremity of the abdomen, and after a time abandoned.
Hummel placed under a bell-glass a female cockroach and a perfect egg-pouch, which had only just been abandoned by another female. He saw the cockroach approach the bag, feel it, and turn it about in all directions. She then took it between her front legs, and made a longitudinal opening in it. As the opening grew wider, little white larvæ were seen to come from it rolled up and attached together. The female presided at this operation. She assisted the larvæ to set themselves free, aiding them out gently with her antennæ. In a few seconds they were able to walk, when she ceased to trouble herself about them.
Fig. 301.—The Cockroach (Blatta orientalis).
The larvæ change their skin six times before reaching the perfect state. When they come out of their skin they are colourless, but the colour comes in a few minutes. At the fifth moult, which takes place three months after birth, they become pupæ, with rudimentary wings, the whole shape of the insect being well marked. The sixth, or last moult, takes place at the end of six weeks. The pupa is now changed into a perfect insect. The female is distinguished from the male by the greater size of her abdomen.
The most destructive of the Blattæ, or Cockroaches, are those which have been imported into Europe by the ships coming from the colonies. The Kakerlac Americana is from an inch to an inch and a quarter long. It infests ships, running about at night over the sleeping passengers, and devouring the food. They are to be met with in all parts of the world. They abound particularly in the warm parts of America. The Blatta orientalis is more commonly met with than the above. It swarms in kitchens, in bakers' shops, provision shops, &c., where it hides in the cracks of the walls, or against the hinges of the doors. It is a small hideous animal, of a repulsive smell, and of a reddish brown colour. It is a little larger than the Blatta Americana. In France it is called by various names, such as Cafard, Panetière, Noirot, Bête noir, &c. If in the middle of the night you suddenly enter with a light into the down-stairs kitchens, you will often see these little beasts running about on the table, and devouring the remains of the food with astonishing rapidity.
The largest species of the genus of which we are now treating is the Kakerlac insignis, which inhabits Cayenne and Brazil, and in length sometimes exceeds an inch and three-quarters, and in the extent of its wings four inches and a half.