= ote 
percentage of parasites builds up more rapidly in high populations of E. 
tenellus, which would explain the higher parasitization in new fields be— 
cause new fields as a rule run to high thistle, whereas old fields run 
torLow.”’ 
FOREST INSECTS 
Kites used to trap insects at high elevations.--T. T. Terrell, 
Coeur d'Alene, Idaho, states that in order to learn more of the flight 
habits of the mountain pine beetle (Dendroctonus monticolae Hopk.), “a 
number of weathervane-insect traps were placed along the Continental 
Divide in the Glacier National Park in an attempt to determine whether 
these insects are migrating from the heavy infestation on the west side 
of the park to the uninfested eastern timber stands, On the Beaverhead 
National Forest large Weather Bureau box kites were used to carry insect 
traps to various heights, in the hope of obtaining adults of the moun— 
tain pine beetle. This is the first time that such equipment has ever 
been used for the trapping of insects at high elevations. Although 
the project was not successful in obtaining mountain pine beetles, other 
bark beetles and a number of other insects were taken. This equipment 
offers a cheap and economical method of studying insect flights." 
Record winter kill of western pine beetle in Oregon.—-The aid of 
the low temperatures of. the past winter (1932+33) in effecting contro] 
of the western pine beetle (Dendroctonus brevicomis Lec.) has been pre— 
viously referred to in the Monthly Letter (See Numbers 225, 226). J. A. 
Peal, Portland, Oreg., now reports: "Last winter a new cold weather rec— 
ord for Oregon of 54 degrees below zero was established at Seneca, near 
this area. Examination of infested bark after the freeze showed that at 
least 85 percent of the larvae had been killed. Bark examinations made 
by Beal and three Civilian Conservation Corps helpers showed that on 
the average only 3 beetles per square foot had escaped from overwinter— 
ing trees. This is a reduction of about 95 percent from normal emerg— 
ence and is the most nearly complete extermination of the western pine 
beetle by cold weather of which we have any record." 

seasonal history of mountain pine beetle.--Reporting on studies 
of Dendroctonus monticolae, G. R. Struble, Berkeley, Calif., says) 
"From seasonal—history records obtained from 8 caged trees, 7 trap trees, 
and 6 standing trees attacked under natural conditions, the following 
Salient points are evident: (1) New adults from the first main summer 
generation have been emerging for the past 4 weeks, with the brood stages 
at present from mature larvae to black adults still under the bark; (2) 
the broods reaching most rapid development occur in trap logs or stand— 
ing trees that have not resisted the initial attacks; (3) the period of 
emergence of new adults in a given tree is carried over a period of from 
5 to 9 weeks; (4) a minimum of 5 weeks was required to produce a gener— 
ation of new adults in a trap log from the time of first. attack, and a 
period of 2 to 3 weeks is required between the callow adult stage and 

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