9 



ing small black dots and spots- 

 eventually i-esulting in extensive 

 discolorations. The black oak 

 {Quercus coccinea) sometimes- 

 bears on the upper surface of 

 its leaves numerous ash-gray 

 blotches of irregular size, which 

 «; : when closely examined are found 

 ; to be minutely speckled with 

 black. They are the results ot 

 the growth of another fungua 

 y [Microsphasra quercina), which 

 preys upon the growing foliage 

 of this oak. And so through 

 the whole list of shade and for- 

 est trees, there are very few 

 species that are not subject to 

 Fig. 2. Showing leaf of black one or more of these fungus par- 

 gum gaUed by minute mites asites. The elms, the basswoods,. 

 a, section throigb one of ' ' 



the galls. Soft maples show the hickories, the walnuts, all 

 a similar injury. ^^^^ ^^^^.^ peculiar species. 



With such numbers of enemies, insect and fungus to- 

 drain them of sap and destroy their foliage it might 

 seem that trees would more frequently be destroyed. 

 This result would probably be witnessed more often were 

 it not for the fact that the leaf-eating insects are most 

 common as a rule during dry seasons (this does not 

 appear to be true of insects which live in the interior of 

 plants), while the fungus enemies are most injurious 

 when the rainfall is greatest. Their prevalence being 

 thus alternating to some extent, the trees do not so often 

 suffer from attacks of both at one and the same time. 



The insect pests are the more frequently destructive,, 

 and at times so completely strip the leaves from elms, 

 maples and other trees as to threaten their extermina- 



