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FOREST INSECT INVESTIGATIONS 
P. C. Craighead, Senior Entomologist, in Charge 
J.« Cs Evenden reports that in the past season control operations 
were instituted against an epidemic of Dendroctonus monticolae in the 
lodgepole pitte stand of the Bitterroot and Beaverhead National Forests. 
This outbreak, which began some four or five years ago, has at the pres~ 
ent time reached a tremendous magnitude; on the East Fork of the Bitter 
root River hundreds of thousands of lodgepole pine and yellow pine trees 
are killed each year. Within the past two or three years the insects have 
crossed the Continental Divide- from this area and. established themselves 
in the Beaverhead National Forest, where the infestation, unless checked 
by artificial control, promises to become as serious as that on the Bit- 
terroot Forest, where entire lodgepole pine forests are being destroyed, 
Approximately $17,000 was spent in control work on this. project 
during the past’season. The amount was sufficient for a fairly efficient 
clean-up on the Beaverhead Forest, but permitted the treatment of only the 
extremely advanced groups of infested trees of: the Bitterroot Forest. 
Daring August and September an extensive survey was made of the infested 
"areas by Mr. Evenden, the Bureau's representative in charge of this project, 
preliminary tothe institution of control work in the spring of 192%. This 
survey showed that in the.past season the insects had spread into the areas 
cleaned by coéntrol work. in May and June, in such nuinbers that if these re- 
gions are to be held against the advance of the epidemic there will be more 
trees to treat in 1927 than there were in 1926, | 
During the past.summer.A, L. Gibson, of the Coeur d'Alene, Idaho, 
Station, has been located in temporary field headquarters at Sula, Mont., 
continuing the intensive studies of Dendroctonus monticolae which were 
instituted in 1925. The earlier part of the season was spent in checking 
the results of the control experiments established in the previous season, 
These experiments consisted in felling the. infested trees and removing the 
limbs and tops, felling them and leaving the limbs and tops remaining, fell- 
ing them so that the bole was flat on‘the ground, on logs, and lodged in 
other trees, and girdling standing infested trees. The experiments were 
arranged with a view to securing different degrees of moisture between the 
bark and the wood, in the hope that by some of the methods tried the insect 
broods would be destroyed. An intensive examination was made of these trees, 
and valuable data were obtained relative to the seasonal history and habits 
of Dendroctonus monticolae, as well as of associated insects, predators, 
and parasites, These experiments produced no positive results, but the more 
promising phases were continued on a rather large scale in the latter part 
of the season, It i8 hoped that from a combination of two of these phases 
a satisfactory mortality of the Dendroctonus. broods will be obtained; one 
‘which will warrant the use of the method as more economical than others ( 
which have been tried in controlling Dendroctonus epidemics in lodgepole 
Pine stands. 
The field season has practically come to a close, and Dr. S. A. Graham 
and l. G. Baumhofer have returned to their station at St. Paul, Minn., for the 
winter, 
