[431] SCIENTIFIC MANUAL. 145 



as the lady-birds, tiger-beetles, predaceous ground-bee- 

 tles, and some others, which destroy caterpillars, plant- 

 lice, and other insects injurious to vegetation. Others 

 serve as scavengers, by the removal of carrion, dung, and 

 other filth. Others live altogether on the mushroom fam- 

 ily of plants ; others live under the bark of trees, and in 

 the trunks of old trees, and are injurious, but many of 

 them living mainly upon dead or decayed bark and wood, 

 QO but little damage. 



There are others still, called blistering beetles (canthari- 

 didae), which are employed in the healing art. 



2. "ORTHOPTERA [straight-winged]. (Cockroaches, crick- 

 ets, grasshoppers, etc). Insects with jaws, two rather 

 thick and opaque upper wings, overlapping a little on the 

 back, and two larger, thin wings, which are folded in plaits, 

 like a fan. Transformation partial. Larvae and pupae act- 

 ive, but wanting wings." With one exception, all of the 

 orthoptera are injurious, either to household goods or veg- 

 etation. 



Their larvae closely resemble the perfect insect, and their 

 pupae do not lie in an apparently dormant state like those 

 of the Coleoptera, Lepidoptera, etc., though they shed 

 their skins usually six times during their transformation 

 from the larva to the perfect insect. Unlike insects which 

 undergo a complete transformation, they continue to grow 

 during their transformation, increasing in voracity with 

 their advancement towards maturity, and, unlike the Lep- 

 idoptera, continuing their depredations after maturity. 



Orthoptera are subdivided into 



1st. Runners, such as earwigs and cockroaches, which 

 are provided with legs suited for rapid motion : 



2d. Graspers, embracing mantes or soothsayers, which 

 have teeth on their forelegs suited to grasping other insects, 

 upon which they prey. 



3d. Walkers, such as "walking-sticks," which have long 

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