FOREST INSECTS AND FUNGI 107 



the needles, attacking them at the base. Besides the spruce, 

 other conifers may be attacked. 



Trees may be killed outright by the spruce bud worm, if 

 defoliated repeatedly, but in the majority of cases the result is 

 the checking of the growth of the tree and the weakening of its 

 vitality. Indirectly this is of importance, since the weakening 

 of the tree's vitality results in its falling an easy prey to the spruce- 

 destroying bark beetle, which is a much more dangerous enemy. 

 Branches attacked by the spruce budworm have a reddish- 

 brown appearance, due to the bare twigs and to the dead leaves, 

 which the caterpillars have fastened together to serve as a place 

 in which to live. 



Dr. C. Gordon Hewitt, F.E.S., Dominion Entomologist of 

 Ottawa, Canada, has studied the spruce budworm and the fol- 

 lowing account of its life history is taken from one of his addresses 

 published in the Report of the Canadian Forestry Convention 

 for 191 1 : 



"The winter is passed in the caterpillar stage, as a very small 

 caterpillar, we believe, in a little shelter constructed near a bud. 

 In the spring, when the buds begin to swell, the caterpillar begins 

 to feed and becomes full-grown towards the end of May and 

 beginning of June. They are then four-fifths of an inch long, of 

 a reddish-brown color, and have small light-yellow warts on 

 each segment of the body; the sides of the caterpillar are lighter 

 in color. They transform into brown chrysalids inside the loosely 

 made shelters. In six to ten days the small brown moth emerges 

 from the chrysalis, dragging the empty case partially out of 

 the larval shelter. The moths are found from the middle of 

 June to the end of July. Shortly after emergence, they deposit 

 their peculiar pale-green scale-like eggs in small oval patches on 

 the undersides of the needles, and they are not conspicuous. 

 The eggs hatch in about a week or ten days, and the young 

 larvae feed for a short time on the terminal shoots of the branches 

 before hibernating. During July when the moths are flying, 

 they occur in enormous numbers about the electric and other 

 Kghts. . . . They are carried considerable distances by the 

 wind, and this method of dispersal accounts for the rapid spread 

 of the insect." 



