KEY TO THE ORDERS OF INSECTS. 



1. Wings developed 2 



Wingless, or with vestigial wings 29 



2. The wings of the mesothorax (the fore wings) horny, leathery or parchment- 



like; prothorax large and separate from the mesothorax (except in the rare 



Strepsiptera, which have minute fore wings) 3 



The mesothoracic wings membranous 11 



3. Mesothoracic wings (called tegmina or hemelytra) containing veins, or at least 



the metathoracic wings not folded crossways when hidden under the upper 



wings 4 



Mesothoracic wings (called elytra) veinless, of uniform consistency, the meta- 

 thoracic wings, when present, folded crossways as well as lengthwise when 

 at rest and hidden beneath the elytra; mouth mandibulate 10 



4. Mesothoracic wings of uniform texture, usually with many veins; head verti- 



cal 5 



Mesothoracic wings leathery at the base, membranous at the tip, usually over- 

 lapping the abdomen when at rest; head usually horizontal; mouth beak- 

 like or awl-shaped, fitted for sucking. True Bugs. .HEMIPTERA (Page 76) 



5. Mouth with the mandibles fitted for chewing 6 



Mouth fitted for sucking, the beak arising from the back part of the head and 



projecting backward HOMOPTERA (Page 73) 



6. Hind wings not folded, similar to the fore wings; social species, living in colonies. 



Termites ISOPTERA (Page 17) 



Hind wings folding, broader than the fore wings 7 



7. Usually rather large or moderately large species; antennae lengthened and 



thread-like; prothorax large and free from the mesothorax; cerci present; 



fore wings rarely minute, usually long 8 



Very small active species; antennae short, with few joints; no cerci; fore wings 

 minute; prothorax small. Rare, short-lived insects, parasites of other 

 insects, usually wasps and bees. Males of STREPSIPTERA (Page 41) 



8. Hind femora not larger than the fore femora; mute species; body more or less 



flattened with the wings superposed when at rest; tergites and sternites 



subequal 9 



Hind femora almost always much larger than the fore femora, jumping species, 

 if not (Gryllotalpa) the front legs broadened for burrowing; species capable 

 of chirping or making a creaking noise; body more or less cylindrical, the 

 wings held sloping against the sides of the body when at rest; tergites usually 

 larger than the sternites. Grasshoppers, Katydids, Crickets 



ORTHOPTERA (Page 13) 



9. Body elongate; head transverse, vertical, free, not set into the very long 



prothorax; front legs spined, formed for grasping prey; deliberate movers. 



Mantis MANTODDEA (Page 16) 



Body oval, much flattened; head nearly concealed underneath the oval prono- 

 tum; legs similar and fitted for rapid running, the coxa? large. Roaches 



BLATTOIDEA (Page 16) 

 6 



