70 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. 



fluences soon begin their work of causing decay between the bark and 

 the solid wood ; and this is but the forerunner of greater injury by in- 

 sects which are attracted to the spot, and which, though hidden mean- 

 while from view, soon carry the destruction from the injured to the non- 

 injured parts." 



There is, in fact, more danger that our trees in future (especially the 

 Soft Maple) will begin to fall and perish from the ravages of Borers, 

 as a result of reckless pruning, than that they will ever be seriously 

 or permanently injured by leaf-eaters. These last, as we have seen, 

 may be overcome, but the Borers are not only more deadly but more 

 difficult to manage. 



TREES WHICH ARE UNINJURED. 



I have already indicated a few of the trees which are most subject to 

 injury from this Web- worm. There is also quite a list of trees which 

 are either very little affected or are never attacked, and in this connec- 

 tion it may be well to mention a few of these which are, not only on this 

 account but in every other way, desirable for shade trees and should 

 be strongly urged upon the Parking Commissioners as substitutes for 

 those, like the Box Elders, which are so seriously affected. In this list 

 of desirable trees which have immunity I would mention : 



Tulip tree (Liriodendron tulipifera L.). 



Sweet Gum (Liquidambar styraclflua L.). 



Ssveet Buckeye (JEJsculus flava, Ait). 



Ohio Buckeye (JEsculus glabra, Willd.). 



The Maples {Acer rubrum, A. saccharinum, A. pseudoplatanns, and 

 A. dasycarpum). 



Honey Locust (Gleditschia triacanthush.). 



Kentucky Coffee Tree {Gymnocladus canadensis, Lamb). 



Sour Gum (Nyssa multiflora, Wangerh.). 



Beech (Fagus ferruginea, Ait). 



Yews (Taxus spec). 



GOOD AND BAD EFFECTS OF OUR TREES. 



The beauty of Washington is very greatly enhanced by its shade 

 trees, and the Parking Commission deserve very great credit for the 

 gigantic work they have carried out iu the last fifteen years. But while 

 these trees are and ought to be in the future an uuendiug source of 

 pleasure and healthfulness, yet here, as is so often the case, the good 

 has some corresponding evil. This last, however, may be easily avoided. 

 We hear much of malarial troubles in Washington, and the Potomac 

 flats come in for nearly the entire blame. During the mouth of Oc- 

 tober our streets are constantly covered with fallen leaves from our 

 shade trees, eddying and whirling about and carried by every heavy 





