GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 61 



tions of the foliage to turn brown and die. These causes for anxiety are for 

 the most part vinnecessary on the part of tree owners. 



We believe that the very common and much to be deplored passing of 

 some of our finest oaks and probably maple trees as well may be ascribed 

 indirectly to the drouth of two summers ago and the unusual dryness of the 

 early part of the summer of last year, a dryness which prevailed until late in 

 the summer. Even after the copious rains of early autumn, as some of us 

 will remember, a foot or two below the surface the earth was like dry sand. 

 Manifestly, a tree not properly nourished is going to be less resistant to an 

 attack of any kind than a tree well nourished, just as a human being with 

 insufficient nutrition is going to succumb to disease, other things being equal, 

 more readily than one in proper condition as regards nutrition. 



Assuming that borers attack our trees every year, and they doubtless do, 

 several on the oak and on the maple, one or more on the elm, the same on 

 birch, the enfeebled trees succumbed, many of them last year, not a few 

 this year, as the result of two years' attack, and partly because some of our 

 borers require, we believe, two years to mature. Some of the trees, the con- 

 dition of which are alarming the owners at present, were dead or dying last 

 summer (1911) but their condition may not have been noticed at that time. 

 During the year just passed such trees stood out in sharp contrast to the 

 general dark green of the healthy growth about them. 



It would seem too that the borers are not alone responsible for the death 

 of so many of our oaks. One or more fungous diseases were found working 

 on the roots of doomed trees last summer, and the present condition of our 

 oaks may be due in part to a plant disease, something akin to the disease 

 which is killing the Chestnut trees in the Eastern states. 



It should lie within the province of city park boards to compel owners of 

 real property to take care of trees which are a menace to the property of 

 others and we believe that they should be appealed to in cases of this 

 kind. 



One can generally easily tell whether borers are at work or have worked 

 on dead on drying trees. By removing a little of the bark the burrows of the 

 worms and frequently the worms themselves can be plainly seen. 



Our Cutleaf Birches are very apt to succumb to the attacks of the Bronze 

 Birch Borer. This depredator, too, can be seen by removing a little of the 

 bark from the affected portion of the tree. 



It must be remembered also that leaky gas mains are frequently respon- 

 sible. Many of our trees in the Twin Cities which have been dying owe their 

 death to this insiduous cause. When this is found to be the case, the gas 

 companies should be appealed to to repair the leak and replace the trees 

 killed. 



Where only a few branches of a tree are affected so that pruning is prac- 

 ticable without sei'ious defacement, such branches should be cut off consid- 

 erably below the injured portion and destroyed. 



