360 COLLEGE ZOOLOGY 



their heads are very small, and their legs are fitted for leaping; 

 The larvae feed on decaying animal and vegetable matter. 

 The cat and dog flea, Ctenocephalus canis (Fig. 296), is the most 

 common species. It does not restrict its attacks to the dog, 

 however, but also visits man. The human flea, Pulex irritans, is 

 found all over the world. The rat flea, Lcemopsylla* cheopus, 

 is of considerable importance, since it seems to be able to trans- 

 mit the bubonic plague from rats to man. The jigger or chigoe 

 flea, Sarcopsylla penetrans, burrows into the skin of man and 

 often causes considerable trouble. 



Order 18. Coleoptera. — Beetles (Figs. 297-304). — In- 

 sects with four wings, the fore- wings sheath-like (elytra) and 

 covering the membranous hind wings; biting mouth-parts; 

 metamorphosis complete. 



This order contains a great number of species; there are 

 nearly twelve thousand known in North America, north of 

 Mexico. For convenience they have been grouped into eight 

 suborders. 



Suborder i. Adephaga. (Carnivorous Beetles, Fig. 

 297.) — The four principal families of carnivorous beetles are 



the tiger-beetles (Cicin- 

 delid^e, Fig. 297), pre- 

 daceous ground beetles 

 (Carabid^e) , predaceous 

 diving-beetles (Dytis- 

 ctd,e) , and whirligig- 

 beetles (Gyrinid^e). The 

 - Order Coleoptera Tiger- first twQ f am ili es are ter- 

 beetles, Cicindelid.e. (From Davenport, 



after Packard.) restrial; they remain on 



the ground most of the 

 time, where they are busily engaged in capturing other insects 

 for food. The whirligig- and diving-beetles are aquatic and are 

 modified for life in the water. In general it may be said that 

 the carnivorous beetles and other carnivorous insects are bene- 

 ficial, since they usually destroy insects harmful to man. 



