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FOREST INSECTS Saar 
Black Hiils beetle found missing on the Kaibab plateau.--J. M. Miller, 
in chargo of the Berkeley, Calif., laboratory, reports:"One of the 
spectacular outbreaks cf the Black Hills beetle (Dendroctonus ponderosae 
Hopk.) occurred just north of the Grand Canyon in Arizona during the period 
1918 to 1925, but reports from the Park Service and Forest Service since 
that period indicated that the aoa had ceased to be a factor in the 
ponderosa pine rorests of that region. These reports were recently veri- 
fied by Ansel Hall, chief for ester of the National Park Service, and the 
writer while making an examination of the North Rim forests of the Grand 
Canyon National Park, on October 30 to November 5, 1933. During the 
period of its epidemic outbreak the Black Hills beetle threatened to de- 
plete the parklike stands of ponderosa pine which form the forest cover of 
the Grand Canyon National Park and the Kaibab National Forest. The infesta- 
tion concentrated its attacks in local areas, killing tree groups so large 
that fow living pines survived in some sections. F. P. Keen, who conducted 
surveys throughout these areas, estimated that the total loss from 1919. to 
1925, inclusive, amounted to 511,000 trees, ti a volume of 146,000,000 
board feet. nent rol, work was carried on against the epidemic centers from 
1923 to 1925, and a total of about 60,000 eek were treated. Surveys con- 
ducted during the summer and fail of 1925 indicated that the epidemic was 
Gefinitely on the wane, and in 1926 studies by M. W. Blackman established 
the fact that the infestation, though still, present, had reached a light 
endemic condition which would probably continue. ene surveys by the Bureau 
of Entomology have been cenducted in the area sin 1926; but the absence 
of any active infestation was reflected by corre epee and reports from 
sp 
_Forest officers. During the summer of 1933 the Grand Canyon National Park 
undertook to treat all bark-beetle-infested pine trees within reach of the 
Citizens' Conservation Corps camp located near Bright Angel Point on the 
north rim. Altogether 71 trees were cut and peeled on an area of about 
4,900 acres. These trees were all infested by species of Dendroctonus 
Pier than the Black Hills beetle, and no attacks occurred in groups. The 
infesting species were D. barberi, D. convexifrons, D. approximatus, and 
Ips spp., none of which have been found capable of developing aggressive 
epidemic infestations. On November 1 and 2 the writer covered about 
2. 200 acres by road strips, examining 46 trees that had been killed by 
Baek beetles, but failed to find even one specinen of the Black Hills 
beetle." 
Tree medication as a means of mountain pine bee bebtie control.-~-d. C. 
Evenden,in charge of the Northern mn Rocky Mountain field laboratory, 
Coeur d'Alene, Idaho, reports: "Prior te 1933 experiments had demon- 
Strated the Foasibiiity of destroying broods of mountain pine beetle 
larvae in white pine through an injection cf a solution of sodiun 
arsenate witain 50 or 60 deys following attack. It was found, however, 
that in order to secure uniform brood nortality throughout the trees it 
was necessary to apply the »voison to the entire circumference, which 
made the technic of avplication a difficult procedure. With the idea 
of testing different methods of applying this poison so as to secure 
satisfactory results as well as to determine the economic feasibility 
