FOREST INSECTS AND FUNGI I13 



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 outbreak 

 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. 



Elm-leaf Beetle {Galerucella lutcola). 



Form of Damage. — The elm leaves are skeletonized, and this 

 gives the crown of the tree a brown, scorched appearance which 

 detracts greatly from its beauty. If a tree is defoliated two or 

 three seasons in succession, it is sure to die. The elms of 

 southern New England, especially those in cities and towns, 

 have suffered tremendously from this pest. 



Appearance. — The damage is always done before its extent 

 is apparent. By the middle of summer the infested trees are 

 entirely defoHated. The beetle is about one-fourth inch long 

 with head and wings marked with yellow. The yellow eggs are 

 usually deposited in irregular rows on the under surface of the 



