244 WEST VIRGINIA EXPERIMENT STATION. 



THE PRINCIPAL INSECT ENEMIES OF THE SPRUCE IN WEST VIRGINIA. 



Almost every part of a spruce tree from the roots to the ter- 

 minal twigs, buds, leaves, and cones, may be infested by one 

 or more insect enemies, some attacking the vital parts of the 

 living trees, and thereby cause rapid death, while others at- 

 tack only those which are sickly, dying or dead, and thus 

 hasten the death of the sickly and contribute to the destruc- 

 tion of the wood of the dead ones. Thus it is found that some 

 may be classed as primary enemies, while others are secondary: 

 some are destructive, while others are simply injurious. 



During the investigations, I found that among the large num- 

 ber of insect enemies of the spruce, observed and studied, only 

 a few are of special economic interest as primarily detrimental 

 or destructive in their relation to the spruce timber resources of 

 the State. The vast number of individuals of some of these 

 species, however, and their power of destruction, more than 

 makes up for what is lacking in numbers of species, and the 

 enormous loss they have already inflicted and are capable of 

 causing in the future, demands that they should receive espec- 

 ial attention. 



The principal insect enemies of the spruce, so far as 1 have 

 observed in this State, may be best discussed under two separ- 

 ate heads, viz: bark miners and wood miners. 



BARK MINERS. 



The bark miners include many species which mine through 

 the outer and inner bark on every part of the tree, some preferr- 

 ing to infest that on some particular part, while others make 

 no choice ; some attack the healthy bark on living trees, while 

 others can only live in the bark after active growth has been 

 checked by some other cause ; some mine beneath the bark in 

 the adult stage, for the purpose of excavating galleries in which 

 to deposit their eggs, while the adults of other species simply 

 deposit their eggs in the crevices of the outer bark and the 

 young enter and burrow beneath and through the inner bark 

 or outer surface of the wood. 



