166 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 defoliation 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-bud 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, like 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 larve hatch just as the buds 
unfold, and the youngest leaves are at once eaten. Later 
