84 EBERHARTS OUTLINES OF 



CHAPTER XL 



A Key to the Orders of Insects. 



A. Mouth adapted to biting, i.e., having jaws and mandibles. 



a. Front or upper wings horny or leathery; back wings membranous. 



b. Upper wings hard and opaque, forming a covering or shield for 

 the under ones, which are folded (first like a fan, and then 

 doubled), under them. 



Coleoptera (Beetles). 



bb. Upper wings somewhat thickened to protect under wings, which 

 are folded fanlike, but not doubled. 



Orthoptera (Grasshoppers, etc.). 



aa. All four wings membranous and transparent. 



c. Wings many-veined; abdomen not provided with a sting, 

 nor with an apparatus for depositing eggs (ovipositor). 

 Neuroptera (Dragon-flies, etc.). 



re. Wings few-veined ; abdomen usually provided with a sting, 

 or with an ovipositor. 



Htmenoptera (Bees, etc.). 



AA. Mouth fitted for sucking. 



d. Wings four in number. 



e. Wings having feathery scales. 



Lepidoptera (Butterflies, etc.). 



ee. Wings not scaled. 



Hemiptera (Bugs, Plant-lice, etc.). 



dd. Two membranous wings. 



Diptera (Flies, etc.). 



The spring-tails and bristle-tails, small wingless insects, are often classed *a 

 an order by themselves, called Thtsanoptera. 



