CHAPTER XXI 



Orders Orthoptera, Isoptera, Corrodentia, and Thysauura 



The Orthoptera {6p06<! = straight, i.e., in respect of the 

 fold of the wings, and •7rTeyow = wing) have mouth -parts 

 formed for biting (Fig. 113). The front wings are stiff, and 

 form covers or tegmina (Lat. teginen = ^ cover) for the hind 

 wings. The hind wings are membranous, with radiating 

 veins connected by short cross-veins to form a network, and 



Pm. 113.— Mouth-parts of Cockroach. 



when closed they lie in longitudinal folds, like a fan. 

 Numerous species have no wings, or only rudiments of them. 

 There is no abrupt metamorphosis; the young resemble 

 the adult, except in the absence of wings, which appear as 

 buds at an early moult and gradually increase in size in the 

 course of successive moults. 



The Order embraces earwigs, cockroaches, praying- 

 mantises, stick-insects, leaf-insects, grasshoppers, locusts, and 



