1 66 Control of Parasites 



have the habit of rolling together needles or leaves, within 

 which they pupate. The familiar "moths" of the house- 

 hold are characteristic of this group of depredators in gen- 

 eral appearance and habit. They are much less injurious 

 than the large moths and butterflies, as a rule causing at 

 most only the death of twig ends; yet some are occasionally 

 very destructive, especially to conifers. Among these may 

 be mentioned the Larch-moth, which causes the leaves of 

 the larch to die and drop, and by repeated defoHation brings 

 about the death of the tree; large areas of tamarack in the 

 northern woods have been destroyed by this tiny insect; also 

 the Pine-twister, which kills the end -buds, especially of 

 young trees, and thereby causes a crooked or twisted growth 

 of the stem; and the Spruce-bud Tortrix, which has been 

 responsible for the death of large areas of spruce and fir in 

 New England, in conjunction with the secondary bark-beetles. 



The Pine-hud Worm develops from eggs laid by the moth 

 at the base of the bud of the leader in May; the larva soon 

 develops, enters the bud, hollows it out and burrows back 

 into the twig, in which retreat it winters, renewing its work 

 in spring, and continuing until the moth is hatched, finally 

 causing the death of the twig. Other bud worms vary only 

 in the time of development, some being double-brooded, 

 but all work in somewhat the same manner. The oozing 

 out of resin at the point of entrance, forming a smaller or 

 larger, crusted, resin-gall, is a sign of the presence of the 

 burrowing pests. Some, hke the spruce-bud worm, live 

 on the outside and defoliate leaves, as do the large leaf- 

 eaters. 



The leaf-rollers infesting deciduous trees usually feed only 

 on the outside leaves and buds; the eggs having been laid 

 at the base of the end-buds, the larva? hatch just as the buds 

 unfold, and the youngest leaves are at once eaten. Later 



