2 6o INSECTS 



merely because it would produce conditions less favor- 

 able to insect increase. 



Besides those species devouring foliage above ground, 

 there is a large subterranean population of wire- worms, 

 white grubs, maggots, slugs, and the like that attacks 



FIG. 119. A bill-bug, its larva and work in root of Scirpus. 



the roots of plants. The underground work of plant 

 lice has been already mentioned; the species now 

 referred to are those that actually devour the root 

 tissue or dig into the underground stem so as to destroy 

 or weaken the overground plant. Cabbage, onion, 

 radish and other root maggots, wire- worms, grub- 

 worms, grape-root worms, root-borers all are familiar 



