THE ANIMAL KINGDOM. 195 



When several of these powerful caterpillars attack an 

 elm at the same time it is ruined very rapidly. This insect 

 has sometimes been seen to utterly destroy large avenues 

 of lofty trees : hence the name of Cossas ligniperda (Wood- 

 Destroying Cossus) has been given to it. This Cossus is, 

 unfortunately, common enough in France. Frequently 

 while walking in a plantation of elms we can see on the sur- 

 face of some of these trees holes, from which issues a sort 

 of moist sawdust. These are the entrances to the hidden 

 tunnels gnawed by the larva of the dreaded moth. 



The larva of the Great Capricornis (Cerambyx heros), 

 which mines the interior of ancient oaks, and often injures 

 the most beautiful pieces of carpenter's work, has its back 

 cuirassed with solid wrinkled plates, 1 which serve the same 

 purpose as the chimney-sweep's knee-pads, and protect its 

 skin when it climbs its w r ooden chimneys. 



But we find artisans endowed with a very different kind 

 of ingenuity in a certain tribe of bees called carpenter- 

 bees, from their great skill in working wood. They live 

 principally in tropical countries. One kind, however, in- 

 habits our latitudes ; it has the look of a great humble-bee 

 of the most beautiful blue color, and is known by the name 

 of the carpenter-bee, Megachile Sicula. Impelled merely 

 by maternal instinct, its work, which consists of as many 

 little chambers as it lays eggs, is a masterpiece of skill and 

 foresight. It generally^ attacks beams, cutting in them, 

 lengthwise, canals, which are as much as a dozen inches 

 deep, and more than a third of an inch wide. 



When one of these great excavations has attained its 



1 See the figure on p. 127. 



