202 



SYSTEMATIC ZOOLOGY 



wooden stick or board, leaving only a thin shell on the outside ; 

 the legs of tables may be eaten out in this way. 



Of the lice belonging to this order, there are the book lice, 

 common in old books and papers, wingless insects with which, 

 however, the little, winged psocids are 

 associated ; then there are the bird lice, 

 with biting mouth parts, feeding on 

 feathers, while some closely related 

 genera feed on 

 the hair or wool 

 of main- domestic 

 animals. Finally, 

 in this same 

 order must be 

 classified the 

 thrips, unless 

 they are placed 

 in an order by 



themselves. They are minute insects only two or three milli- 

 meters long, and some are common on the daisy and clover 

 blossoms ; their two pairs of wings are very narrow and 

 feathery. 



.'.-• 



y" 1C-- 



Fig. 197. Mantis religiosa, the praying mantis, 

 preserved specimen.) 



(Drawn from a 



Order 3. Orthoptera 



The Orthoptera (Gr. 6p96$, straight, and irrepov, wing) include 

 some of our commonest insects, such as the cricket, grass- 

 hopper, locust, cockroach, katydid, and 

 earwig. They have two pairs of wings, 

 the anterior pair thickened and straight, 

 the posterior pair thin, larger, and folded 

 lengthwise like a fan when at rest. But 

 many genera are wingless, and some have 

 the anterior pair only. The month parts 

 are well developed, and all the Orthoptera, 

 with the exception of the praying mantis 



fig. 198. LaUdura riparian, (Fig- 197). are more or less injurious to 



enlarged; an earwig. (From vegetation. Many females have a special 



Ludwig-Leunis' Synopsis der J 



Thieikunde.) appendage at the posterior end of the 



