ARTIIKOl'ODA 



205 



of more or less membranous wings, with mouth parts adapted 

 to sucking, and pass through an incomplete metamorphosis in 



Fig. 201. Phyllium sicci/olium, the leaf insect. 

 (From Brehm's Thierleben.) 



Fig. 202. Gryllus domes- 

 ticus, f, the common 

 dark brown cricket. 

 (From Ludwig-Leunis' 

 Synopsis der Thier- 

 kunde.) 



the course of their development. They include various kinds 



of bugs and lice. These insects may be considered best under 



three groups : the first comprises those wingless parasites on 



man and other mammals, commonly 



called lice ; the second has the 



anterior pair of wings of uniform 



thickness throughout ; the third has 



the anterior pair of wings thickened 



at the base and thin at the tip ; 



these three groups are recognized 



as suborders in the system of 



classification. 



The first includes three species 

 of lice found on the human body ; 

 they pierce the skin and suck the 



J - , Fig. 203. Locusta. (brom Cuviers 



blood ; one infests the hair of the Animal Kingdom.) 



