CLASSIFICATION OF INSECTS. 83 



like with a club at the tip, which is never recurved so 

 as to form a hook. The abdomen is slender (Figs. 

 75. 76). 



Fig. 76. — The banded-purple butterfly. 



Order Diptera (Dip'te-ra). 

 The Flies. 



The members of this order have only two wings ; 

 these are borne by the mesothorax. The metathorax is 

 furnished with a pair of knobbed threads — the halteres. 

 The mouth-parts are formed for sucking. The meta- 

 morphosis is complete. 



To the order Diptera belong all insects that are 

 properly termed flies, and only these. The word 

 " fly " forms a part of many compound names of in- 

 sects of other orders, as butterfly, stone-fly, May-fly, 

 and Chalcis-fly ; but when used alone, it is correctly 

 applied only to dipterous insects. To some flies 

 other common names have been applied, as mosquito, 

 gnat, and midge. 



The name Diptera is from two Greek words : dis, 

 two, and pteron, a wing. It was suggested by the 

 fact that the flies are distinguished by the possession 



