218 



SYSTEMATIC ZOOLOGY 



with the body compressed laterally, and live for the most part 



as external parasites on the skin of mammals. The larvae in 



their form and habits of life resemble the larvae of some Diptera. 



A 



FIG. 221. a, Pulex avium, '. A, antenna : Mi, maxillary palp, b, Pulex irritans, larva. 

 Highl) magnified. (From Claus and Sedgwick's Text-book.) 



Order 8. Coleoptera 



The Coleoptera (Gr. /coXeos, sheath, and inepov, wing) are 

 commonly called beetles and include a very large number of 

 species. They arc readily distinguished from other insects by 

 the thickened anterior wings (Fig. 222), which are called the 



elytra and form covers for the 

 delicate, membranous posterior 

 wings, which are folded beneath 

 them ; in a few cases the posterior 

 are wanting. The mouth parts 

 in this order are adapted to biting, 

 and the development is attended 

 by a complete metamorphosis. 

 The prothorax is often relatively 

 larger than in many insects, and 

 is sharply marked off from the 

 "thorax, so that, seen from 

 the dorsal side, the bodv appears 

 to consist of head, prothorax, and elytra, which in most beetles 

 completely cover the abdomen. The antennae vary greatly both 

 in length and shape. The legs are for locomotion and differ 

 according to the habits of the species. 



I'll ;. 222. Calosoma, a ground beetle with 

 n-gold wings. (Drawn from speci- 

 men. ) 





