February, ’23] graham & ruggles: economic entomology and forestry 57 
METHODS OF ATTACKING THE FOREST ENTOMOLOGICAL PROBLEM 
The difficulty of a problem in forest entomology is directly propor¬ 
tional to the distance between the wood or tree and the finished product. 
We can afford to spend more in protecting material at the mill than could 
be spent on the same material in the woods. We can spend more on 
cut timber than on standing timber. The nearer a tree approaches 
commercial maturity the greater its value and the more we can put into 
its protection. During their early years the trees must practically 
be left to take care of themselves, since a good profit on the final crop 
can be wiped out easily by compounding interest even on small injudicious 
expenditures in the early years of the rotation. When these facts are 
considered it appears probable that insect problems connected with for¬ 
est products are likely to be the simplest whereas those connected with 
young trees are likely to be the most difficult. This is borne out by 
the fact that many of the problems connected with the control of insects 
in forest products have already been solved. In this work mechanical 
means of one kind or another are usually resorted to with more or less 
satisfactory results. Therefore let us turn our consideration to that 
phase of forest entomology most neglected, that is the control of insects 
attacking living trees. 
There are two distinct angles from which insects infesting standing 
timber may be attacked. These are, first from the point of view of 
checking outbreaks after the insects have actually become active and, 
second, the prevention of outbreaks. 
Checking active outbreaks of insects must necessarily depend very 
largely on mechanical methods of control. Our outstanding examples 
of the successful checking of outbreaks are to be found in the opera¬ 
tions against the Dendroctonus beetles in the West. These operations 
have been expensive and difficult, but the protection of valuable stand¬ 
ing timber has doubtless justified the outlay of time and money. In 
checking epidemics of leaf eating insects we are at present almost help¬ 
less. Spraying or dusting forests with poisons has been considered 
impractical if not impossible and this is almost the only means that 
economic entomology has devised which has even the slightest chance 
of being applied in forest work. Recently experiments in Ohio and in 
New England have demonstrated the possibility of spraying areas of 
considerable size by means of a dusting machine attached to an airplane. 
By this method the work can be carried on very rapidly and with a 
cheap poison the nost might be brought within the realm of possibility. 
But it has yet to prove itself economically practical for forest work. 
