164 EVENINGS AT THE MICROSCOPE 



CHAPTEK 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 ele- 

 ments. You would not think so, indeed; you would nat- 

 urally 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 cut- 

 ting lancets of a Horsefly, 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 instru- 

 ments 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 Carabidce, 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 square, 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 nature, 



