FOREST INSECTS AND FUNGI 105 



of the needles. Individually they are almost too small to be 

 seen with the naked eye, but their number at this stage is legion. 

 They soon attach themselves to the tender bark of young twigs, 

 increase rapidly in size and darken down to brown or black, 

 and all the while exude a substance which nearly conceals them. 

 Maturity is reached about the last of May when the females 

 deposit eggs for another brood. During the summer there may 

 be several broods and at last females with wings appear. 



Treatment. — The aphid has several natural enemies, the 

 most effective being certain varieties of ladybugs. Where a hy- 

 drant is near the insects can be washed off by a forcible stream 

 of cold water. A spray of kerosene emulsion, or whale-oil soap, 

 is efhcient. One pound of the soap to four gallons of water 

 makes a good mixture. However, in forestry it is usually im- 

 practicable as well as unnecessary to use preventive measures. 



The SpRUCE-DESTROYrNG Beetle^ {Dendroctouus 

 piceaperda). 



Form of Damage. — This insect, which has been prevalent in 

 New England and New York since 1818, has destroyed much 

 spruce timber by its borings in the cambium, the living tissue 

 just beneath the bark. Here it makes its primary galleries, 

 and lays its eggs. As soon as the eggs hatch the young broods 

 make transverse galleries which effectually girdle the tree, and 

 in time the withering leaves proclaim the death of the tree. 

 The falling leaves are an outward sign of the damage; by remov- 

 ing the bark the galleries made by the insects may be plainly 

 seen. 



Appearance. — The adult is a reddish-brown or black beetle, 

 varying in length from three-sixteenths to one-quarter of an inch. 

 The egg, small and nearly white, is not distinguishable from that 

 of other bark beetles. The larva, at first a minute white grub, 

 becomes about one-quarter inch long. The pupa is nearly white 



* See " Some of the Principal Insect Enemies of Coniferous Forests in the 

 United States," by A. D. Hopkins, from Yearbook, U. S. Dept. of Agriculture, 

 1902. 



