FOREST INSECTS AND FUNGI 117 



forty or fifty eggs may be found on a single green shoot. As 

 they are usually deposited along one side of the shoot the in- 

 juries inflicted by the saw-like appendages of the female cause 

 the shoot at it grows to curl. In many cases the injuries are so 

 severe as to kill the shoot and the presence of the dead and 

 reddish-brown shoots often serves as an indication of the pres- 

 ence of the insect. In about a week to ten days after deposition 

 the eggs hatch and the young pale-green caterpillars emerge 

 and immediately begin to feed upon the green verticles of the 

 leaves. As they become older they feed in masses, sometimes 

 as many as fifty or sixty caterpillars in a single cluster and, 

 feeding in this manner, they completely strip the branches of 

 all green leaves which gives the tree a winter aspect in the middle 

 of summer. The caterpillars are full grown in three to four 

 weeks and, during their lives, they cast their skins five times. 

 . . . The full-grown caterpillar measures about two- thirds of 

 an inch in length. Its color is bluish or glaucous green, the 

 lower surface being a lighter green. The head and three pairs 

 of thoracic legs are jet black. It also possesses seven pairs of 

 abdominal legs. When the caterpillars are full-grown they either 

 crawl down or drop from the tree and penetrate the turf round 

 the base of the tree to the depth of a few inches. There they 

 spin a brown oval cocoon about two-fifths of an inch in length, 

 and in this the winter is passed, the caterpillar transforming 

 into the perfect insect in the following year as previously de- 

 scribed. The sawflies are black with the middle portion of the 

 hind body or abdomen a bright resin red, and they measure 

 about half an inch in length." 



Treatment. The prevention of the ravages of this insect 

 must be left to natural factors, especially to various parasites 

 which prey upon the sawfly. So completely does an out- 

 break of the sawfly destroy the larch, that the supply of food 

 for the insect becomes scarce and it falls a victim of its own 

 rapacity. 



In Europe birds have been found to be important enemies of 

 the sawfly, and special steps are taken to increase their numbers, 

 but this will hardly be practicable as yet in this country, as the 

 native larch is most abundant in sections where only extensive 

 methods of management can be applied. 



