24 
NEED OF FURTHER INVESTIGATION. 
While considerable evidence was found during the time devoted to 
the investigation, there yet remains much to be determined by detailed 
study and experiments relating to the peculiar conditions which bring 
about the invasion of a rare or new insect and the conditions which con- 
tribute to its rapid multiplication and destructive work, as well as those 
which contribute to its decline and sudden disappearance. There are 
also many facts, yet to be determined, relating to the life history and 
peculiar habits of the pine-destroying beetle and other numerous 
enemies of the trees, and the natural enemies of such insects. The 
determination of these facts is very necessary in order to suggest the 
best methods of preventing losses in the future. It will also help us 
to utilize nature’s methods of protecting such of the species as are of_ 
use to man and destroying those that are objectionable. 
Cutting and barking the infested trees this winter would be an exper- 
iment of great importance, not only in its prospects of ending the 
trouble, but in demonstrating whether or not it is a practicable method 
to be adopted under similar conditions in the future. It will also be 
of interest, and probably of considerable economic importance, to note 
the effect that this process of insect destruction will have on the other 
injurious and beneficial insects involved. 
The experiments of girdling, cutting, and treating trees with a view 
of rendering them attractive to the migrating beetles, and thus pro- 
viding traps for them, is a line of work which should receive special 
attention next summer. It would serve to demonstrate, or at least 
indicate, several things which it is quite necessary to know in order 
to adopt successful methods of preventing future trouble from insect 
ravages on the pines of this reserve. It would demonstrate whether 
or not the beetles that emerge from the infested trees which have not 
been cut and barked could be attracted to trap trees; how and when 
the rock pine can be girdled or treated to exert the greatest attraction 
to the principal enemies, and how the insects thus trapped can be 
best destroyed. It would also contribute greatly to the study of the 
life history and habits of the primary and secondary enemies of the 
trees and the enemies of the insects. 
There are other features relating to the kinds of insects and fungi 
that attack trees girdled by different methods, or girdled and felled at 
different times of the year, which should be determined. Indeed, 
there are many and varied subjects relating to the insects of the rock 
pine which should be studied during the progress of the present 
trouble, in order to accumulate data that will be of service in prevent- 
ing and checking future destructive invasions in the pine forests of the 
Rocky Mountain region. 
O 
