CHAPTER XIII. 



THE COCKROACH. 



THE Common Cockroach (Periplaneta (Blatta) orientalis) is not 

 an indigenous insect, but an immigrant from the East that has 

 domesticated itself in European kitchens. Although commonly 

 called a black-beetle, the cockroach does not belong to the 

 true beetles (Coleoptem\ but to a less modified group of insects, 

 including the Locusts and Grasshoppers, known as Orthoptera. 

 Unlike the higher and more modified insects (Butterflies, House- 

 flies, Beetles, Bees, Ants), which undergo post-embryonic 

 metamorphoses, passing through a soft-bodied, worm-like larva 

 stage, and an inactive pupa or chrysalis stage, the cockroach, 

 though it exhibits a certain amount of development after birth, 

 undergoes no true post-embryonic metamorphosis. The minute 

 cockroaches that emerge from the egg are little white six-legged 

 creatures, with black eyes and without wings. They change 

 their skin, or moult, seven times, rudiments of wings and wing- 

 covers making their appearance in the later larval stages. After 

 the seventh ecdysis (which is said to occur when the insect is 

 about four years old) the cockroach is adult. Those insects 

 which undergo complete metamorphosis are known as Holometa- 

 bola, while those in which the metamorphosis is absent or, as in 

 the cockroach, incomplete, are grouped together as Ametabola. 

 In this respect, therefore, and in certain others, the cockroach is 

 a little-specialised or primitive insect. Its family is also a very 

 ancient one, remains of cockroaches being found in the Silurian 

 strata. 



External Characters. The body is marked out into distinct 

 regions. A well-developed head is followed by a narrow neck, 

 17 



