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Chapter IX. 

 THE COCKEOACH. Periplaneta Americana. 



The common cockroach or ' black beetle ' of our kitchens and 

 bakehouses — Periplaneta {Blattd) orientalis — is not a true 

 beetle, but an insect belonging to the order Orthoptera, of 

 which grasshoppers, locusts, and crickets are also members. 

 This species differs only slightly from P. Americana, which 

 has been chosen for description because it is larger and more 

 easily dissected than the common form. P. Americana may 

 be found in large numbers on board ships and at most docks. 



Cockroaches are active insects, of nocturnal habits, hiding 

 away in the daytime and coming out to feed at night. They 

 will devour almost any animal or vegetable substance. 



The whole animal is covered by a chitinous cuticle which 

 is thick and hard, and of a dark-brown colour, except at the 

 joints, where it is soft and paler. By these joints the body is 

 divided transversely into segments, which are movable on one 

 another except in the head. As in the crayfish the segmenta- 

 tion affects certain of the internal organs, as the muscular and 

 nervous systems, but is not shown by the digestive, excretory, 

 or reproductive organs. 



The female lays its eggs in a hard oblong capsule, in which 

 they are placed side by side. The young develop without 

 metamorphosis, i.e. when newly hatched they resemble the 

 adult in form and habits, though they are devoid of wings. 

 During growth the cuticle is shed several times. The wings 

 appear at the last ecdysis, when the animal attains sexual 

 maturity : the female of P. orientalis is, however, wingless. 



M 



