INSECTA: COLEOPTERA 



263 



Weevil, which has a long snout, lives, when a larva, inside 

 hazel nuts. Another attacks the flower-buds of fruit trees, 

 especially the apple. Again, the felled wood of pine trees, 

 stored grains of wheat, the roots and stalks of turnips and 

 cabbages, and parts of many other plants are attacked by 

 these voracious creatures. 



The Birch Weevil (Fig. 197) is one of the most interesting, 

 because of the clever way in which it cuts a leaf from margin 

 to midrib on both sides, and then rolls the lower part into a 

 narrow cone to protect the eggs which it lays within, closing 

 the cone at its lower 

 end by rolling the tip 

 and tucking it in — a 

 wonderful case of an 

 inherited complex in- 

 stinct, the evolution 

 of which it is ex- 

 tremely difficult to 

 understand. The blind 

 larva lives inside the 

 funnel until it is full 

 grown, feeding on the 

 leaf. 



The Common A com- 

 Bark Beetles mon Bark 

 (Scolytidae). Beetle is 

 Hylesinus fraxini, 

 which occasionally 

 does much damage to 

 ash trees. It is a 

 tiny beetle which bites 

 through the bark of 

 the tree, and then 

 excavates a little hori- 

 zontal tunnel in the 

 wood just inside the 

 bark (Fig. 198). In 

 small bays in the 

 side of this tunnel the beetle lays her eggs, and the maggot- 

 like larvae which hatch out, feed on the tissues of the wood, 

 eating little tunnels which pass out at right angles to the 



Fig. 198. — The Bark Beetle (Hylesinus fraxini 

 n, Entrance to horizontal tunnel made by the mother 



beetle ; t, vertical tunnel made by her offspring ; 



b'j cell in wliich the larva pupates ; a', a hole 



through which a daughter beetle has emerged ; c, 



one beetle enlarged. 



