134 THE CULTIVATED EVERGREENS 



with whale-oil soap — one pound in two gallons of water — 

 will give effective control. The lice are destroyed in great 

 numbers by insect enemies, and artificial control measures 

 are rarely necessary. 



The spruce hud-worm {Tortrix fumiferana, Clemens). 



The most serious pest of the great spruce forests of the 

 northern United States and Canada is a bud-worm, the larva 

 of a small light-brown, gray-mottled moth. Outbreaks occur 

 at intervals of several years and large areas of forests are 

 defoliated and in many cases killed. At such times ornamental 

 trees do not escape attack, but may be seriously injured by the 

 small caterpillars. 



The caterpillars hibernate in an early stage of their develop- 

 ment and resume feeding in the spring as soon as the new 

 growth appears. They cut off the needles at the base and then 

 web them together with silk, forming a loose shelter in which 

 they live and continue feeding. The caterpillars become full 

 grown about the middle of June in Maine and pupate within 

 the web. The moths emerge a week or ten days later and lay 

 their eggs in small oval clusters on the spruce needles. The 

 eggs hatch in about a week and the young caterpillars feed 

 on the opening buds. There is only one brood a year. 



On ornamental trees the spruce bud-worm may be controlled 

 by spraying in the spring, just after the buds open, with 

 arsenate of lead — three pounds of powder in one hundred 

 gallons of water. The application should be repeated a week 

 or ten days later. 



The larch case-bearer {Coleophora laricella, Hiibner). Fig. 16. 



Young, vigorous larch trees are frequently attacked by a 



small case-bearer that mines in the leaves, causing a yellowish, 



unhealthy appearance of the foliage. Badly infested trees may 



