WEALTH OF INSECT LIFE 165 



differentiation the character of the organs of flight, and 

 the structure of the mouth-parts. Exceptions to the 

 arrangement can be found in every order given. The 

 same may be said of any system thus far proposed. 

 This method commends itself for its simplicity and the 

 uniformity of its nomenclature. 



Insects, then, according to this system are grouped 

 into nine orders, and the names of these are formed 

 of words compounded with the Greek root, vrrepdv, 

 pteron, meaning wing. These are: Aptera, ISTeurop- 

 tera, Orthoptera, Tliysanoptera, Hemiptera, Lepidop- 

 tera, Coleoptera, Diptera, and Hymenoptera. The 

 character of the mouth-parts is designated by the terms 

 biting and suclclncj, the former referring to that form 

 of mouth in which the mandibles and the maxilke, or 

 either one, are used in grasping, biting or masticating 

 the food; the latter pertains to that form of mouth 

 adapted for sucking. A discussion of the chief char- 

 acteristics of these orders is given, and some of the more 

 prominent subdivisions, as well as characteristic forms, 

 are briefly treated. 



APTERA. 



This term, Aptera, is derived from a, without, and 

 TrrepoV, pteron, a wing. The insects coming under this 

 order are therefore wingless. Mouth-parts mandibulate, 

 metamorphosis slight, the adult form being the same as 

 the larval form. They have a delicate outer skin, 

 sometimes covered with scales. Though somewhat 

 primitive in form, they are so diverse in their individ- 

 ual structures that it is difficult to frame a definition 

 which will include all the group. While it is true that 



