62 A BOOK OF INSECTS 



smaller species, known as Labia minor, is also abundant. 

 The order Dermaptera includes the small family Hemi- 

 meridue. These remarkable insects are blind and wingless. 

 They inhabit West Africa, and one species is known to 

 live among the hairs of a rat or " ground pig," and other 

 small mammals, and is believed to prey upon the parasites 

 of its hosts. 



Order III. — Orthoptera. 



This order includes the cockroaches, mantids, " stick " 

 and " leaf " insects, locusts, grasshoppers, and crickets. 

 They agree in possessing biting mouth -parts, while the 

 second maxillae are not so closely fused together as in 

 most other insects. Their metamorphosis is always in- 

 complete. When present the fore-wings are modified 

 into leather wing-cases, or tegmina, which close over and 

 protect the delicate, fan-like hind-wings when the insect 

 is at rest. Many species, however, are wingless. Orthop- 

 tera fall naturally into two groups. In the first, which 

 comprises the cockroaches, mantids, and stick insects, the 

 hind-legs are formed for running or walking. 



The cockroaches (Blattidce) are especially characteristic 

 of tropical countries. There are only three indigenous or 

 " wild " British species. These live among moss, dead 

 leaves, and low-growing herbage ; and in the summer they 

 may sometimes be seen in numbers flying from one leaf 

 or stem to another, or basking in the sun's rays. Several 

 species of cockroaches, however, frequent houses and 

 ships, and have become almost cosmopolitan in their 

 range. Of these the best known are the German cock- 

 roach (Pky/lodromia germanica), the American cockroach 

 (Peripkmeta americana), and Blatta orientalis — which is 

 the common " black beetle " of our kitchens. This insect 



