XI 



PHYLUM ARTHROPODA 



585 



the other segments of the thorax. The metamorphosis is some- 

 times complete, sometimes incomplete. 



This order includes Termites (" White Ants "), May-flies r (Fig. 

 470), Dragon-flies, Ant-lions, Caddis-flies. 



ORDER 4. HEMIPTERA. 



Insects in which wings are usually present, sometimes similar, 

 sometimes dissimilar, and in which there is a jointed suctorial 



FIG. 471. Aphis rosse and larva. (From Cuvier's Animal Kingdom.) 



strum formed from the labium, enclosing the jaws in the form of 

 piercing organs. The prothorax is free from the other segments 

 of the thorax. The metamorphosis is incomplete. 



FIG. 472. Cicada. (After Gutrin and Percheron.) 



This order includes Bugs, Water-bugs. Lice. Scale-insects, Plant- 

 lice (Fig. 471), Cicadas (Fig. 472). 



ORDER 5, 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 adapted for piercing and 

 sucking. The prothorax is fused with the other segments of the 

 thorax. There is a complete metamorphosis. 



This order includes Fleas, Gnats and Mosquitoes (Fig. 473), 



