138 EVENINGS AT THE MICROSCOPE. 



CHAPTER IX. 



INSECTS: THEIR MOUTHS. 



THE parts of the mouth in different Insects afford an. 

 almost endless store of delightful observations ; and the 

 more as, with all their variety, they are found to be in 

 every case composed of the same essential elements. 

 You would not think so indeed ; you would naturally 

 suppose looking at the biting jaws of a Beetle, the 

 piercing proboscis of a Bug, the long, elegantly- coiled 

 sucker of a Butterfly, the licking tongue of a Bee, the 

 cutting lancets of a Horse-fly, and the stinging tube 

 of a Gnat that each of these organs was composed on 

 a plan of its own, and that no common structure could 

 exist in instruments so diverse. But it is so, as we shall 

 see. 



We may consider the various organs of the mouth 

 as most harmoniously and perfectly developed in the 

 active carnivorous Beetles, the Carabida, or ground- 

 beetles, for instance. Let us examine the head of 

 this black Scarites from the garden ; and first from 

 above. 



In front of the polished head-shield, and jointed to it 

 by a broad transverse straight edge, is a four-sided piece, 

 forming an oblong figure, nearly twice as broad as long, 

 a little convex, and marked with six little pits or sinkings 

 of the surface, along its front edge. This is the upper 

 lip ; but, instead of being fleshy, as ours is, it is composed 

 of a hard polished black shelly substance, of a peculiar 



