Boring Insects 



will not be likely to be injured. For surface grubs, 

 cockroaches, and the Otiorrhynchus weevils heaps of 

 clover dipped in lead arsenate may be placed on the 

 soil near the plants attacked. For two-winged flies 

 like the onion fly and for ants, syrup to which arsenic 

 has been added wiU prove attractive and deadly. 



Trees in a weakly condition often form attractive 

 traps for bark beetles (Scolytus) and boring insects 

 such as the shot-hole borer (Xyleborus). If they are 

 cut down when the pests are at work and promptly 

 burned the pests will be destroyed. 



Bread treated with phosphorus paste is useful not 

 only against mice and rats but against cockroaches, 

 two or three species of which often do a great deal of 

 damage to plants growing under glass. Even more 

 effective is an ingenious trap where bran is the bait 

 and an enclosed water reservoir the death-trap. 



XIII. Direct Action. — Where large boring cater- 

 pillars like the goat moth in willow, ash, elm, or 

 chestnut, and the wood-leopard in apples, pears, and 

 other trees are at work, the most effective method of 

 treatment is to thrust a sharp -pointed piece of wire 

 into the burrows where fresh sawdust is to be seen. 

 If it comes out wet its work is done. 



XIV. Fumigation. — Where insects are feeding in 

 enclosed spaces, or where they can be enclosed, the 

 most effective treatment is to fumigate. The effect 

 of smoke from a tobacco-pipe upon greenflies is well 

 known to all, and nicotine preparations are put upon 



129 K 



