XI 



PHYLUM ARTHROPODA 



619 



This order includes Bugs, Water-bugs, Scale-insects, Plant-lice 

 (Fig. 519), and Cicadas (Fig. 520). Lice (Anoplura), wingless 

 parasites of mammals, are usually looked upon as degenerated 

 members of the Hemiptera. 



Fig. 520. -Cicada. (After Guerin and Percheron.) 



ORDER 7. DIPTERA. 



Insects provided (except in the Fleas) with a single pair of 

 transparent membranous wings, 

 representing the anterior pair of 

 other orders. The mouth-parts are 



FIG. 521. Culex (mosquito) and larva. 

 (After Guerin and Percheron.) 



FIG. 522. Bot-fly of the horse (Gastro- 

 philus equi). a, mature insect ; b, 

 egg attached to a hair ; c, d, and e, stages 

 in the larval development. (After Brehm.) 



adapted for piercing and sucking. The prothorax is fused with the 



other segments of the thorax. There is a complete metamorphosis. 



This order includes Gnats and Mosquitoes (Fig. 521), House-flies 



