58 
JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 16 
Even though the economical application of poison to forest areas 
proves a practical possibility we still know little or nothing of the effect 
that the extensive application of a poison would have upon forest life 
in general. The trees, the underbrush, and the ground would be un¬ 
avoidably covered with poison dust. Considerable quantities of poison 
would certainly fall upon the surface of the lakes and streams, and still 
more would be washed into such waters by rains. What will be the 
effect of this poisoning to fish and other aquatic life? How will bene¬ 
ficial insects such as parasites and predaceous forms be affected by the 
treatment ? Since birds feed largely upon insects, what will be the effect 
upon bird life in the sudden reduction of their food supply? Will the 
game or the small mammals inhabiting the forest be injured by the 
poison? In applying such methods of control we must remember that 
trees are not the only things of economic importance in a forest. We 
must also remember that the maintenance of the biotic balance within 
a forest reduces decidedly the chance that any pest will become epidemic. 
It is decidedly possible that dusting operations once started might so 
upset this desirable balance of environmental factors that yearly treat¬ 
ment would be necessary and cause in the long run more harm than good. 
At any rate, even though the airplane did furnish an economical means 
of application, and even though a cheap and effective poison could be 
found in sufficient quantities to make wholesale application a possibility, 
we must certainly answer to our own satisfaction the above questions 
before a general policy of poisoning for forest insect control can be 
safely advised. 
Even at best mechanical methods of forest insect control are always 
expensive and at present can only be used under particularly favorable 
conditions; so unless we can find some cheaper effective means than those 
at present available it is difficult to see how we can ever expect to get 
really satisfactory results from the use of such methods. After in¬ 
sects become epidemic in a forest we are almost forced to use some me¬ 
chanical means if thev are to be checked at all. Therefore let us con- 
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sider the possibility of limiting or actually preventing insect injury to 
the trees by the proper management of our forest lands, that is to 
say, silvicultural control. 
This is a very recent development in forest entomology, but there has 
been enough work done along this line to show decided possibilities. 
In fact it shows us a way to check the losses due to forest insects without 
materially increasing the cost of producing lumber. It has already 
