294 



The Black Spruce, 



which have similar habits, we have found in abundance on 

 the spruce in Maine, where it produces swellings at the 

 end of the twigs, resembling in size and form the cones of 

 the same tree. " I have seen it but once and then on a 

 single tree so that it is not probable that any considerable 

 injury is wrought by it to the spruces in our state. 



Another more common but somewhat similar affection 

 I have observed in many localities. It is most abundant 

 on young trees growing in open places. The tips of the 

 affected branches are covered by crov^ded, incurved dead 

 leaves. At a distance they might be mistaken for the 

 mature cones of the tree. A close examination shows that 

 there is a kind of gall or swelling at the base of each leaf, 

 the little brown scale upon which the leaf stands being ir- 

 regularly enlarged and excavated on one side. Common 

 as are these affected branchlets I have never seen the insect 

 that does the mischief. From the character of the injury 

 it is almost certain that it is produced by some minute 

 plant louse or gall making insect which inhabits the con- 

 cavity and appropriates to itself the juices that should 

 go to nourish and sustain the leaf. Usually the growth of 

 the affected twig is stopped, but sometimes the branch is 

 prolonged beyond the injury. Although the tree is injured 

 I am not sure that it is ever killed by the attacks of this 

 parasite. The third insect foe is one much more to be 

 dreaded and one before whose ravages all other, injuries 

 dwarf into insignificance. If we except the destruction 

 caused by man himself probably all other agencies com- 

 bined do not destroy as man} 7 spruces as the one which we 

 shall presently bring to your notice. I quote the whole 

 account of it from my annual report recently made to the 

 Board of Regents of the University. 



In my last report allusion was made to the fact that 

 the spruce trees in some parts of the great northern 

 wilderness were said to be dying at an unusual rate as if 

 affected by some fatal disease. In the absence of any per- 



