280 MANUAL OF ZOOLOGY. 



posterior, semi-coriaceous or leathery, usually with numerous 

 nervures, the interspaces between which are filled with many 

 transverse reticulations ; sometimes overlapping horizontally 

 (Cockroach), sometimes meeting like the roof of a house 

 (Grasshoppers). Posterior wings usually having their front 

 portion of a different texture from their hinder portion, this 

 latter being almost always more transparent, and when not in 

 use, folded longitudinally like a fan. Posterior wings mostly 

 wanting in the females of the Blattida. Antennae usually 

 filiform. Metamorphosis semi-incomplete (sometimes, how- 

 ever, the adult is apterous, when it becomes almost impossible 

 to distinguish the larva, pupa, and imago). 



This order includes the Crickets (Achetind), Grasshoppers 

 (Gryllina), Locusts (Locustina), Cockroaches (Blattina, fig. 109), 

 &c. Some of them are formed for running (cursorial], all the 

 legs being nearly equal in size ; whilst in others the first pair 

 of legs are greatly developed, and form powerful raptorial 



Fig. no. Migratory Locust {Acrydium migratoriuni). 



organs, as in the Mantis, In others, again, as in the Grass- 

 hoppers and Crickets, the hindmost pair of legs are greatly 

 elongated, so as to give a considerable power of leaping to 

 them. All the Orthoptera are extremely voracious, and the 

 ravages caused by locusts in hot countries are well known to 

 all. The most destructive of the Locusts is the Migratory 

 Locust (Acrydium migratorium, fig. no) of Africa and Southern 

 Asia. This formidable species is celebrated for the destruc- 

 tion which it causes in certain seasons in the countries in 

 which it occurs, a destruction against which human art has 

 hitherto proved wholly powerless. Vast hordes of this species 

 descend suddenly upon a district, and in a few hours destroy 

 all crops, and devour the leaves of all the trees, migrating as 

 suddenly as they came, so soon as the ground is utterly bare. 

 ORDER VI. NEUROPTERA. Mouth usually masticatory ; 



