METHODS 



Twelve beetle-infested lodgepole pines were selected for sampling over a period of 

 time on the Wasatch National Forest south of Evanston, Wyoming. Four of the trees were 

 20 to 28 cm d.b.h., four trees 30 to 36 cm d.b.h., and four trees 38 cm and larger d.b.h. 

 A chain saw was used to cut two vertical slots into the trunk of each tree for film 

 placement, a technique explored by Berryman and Stark (1962b) . This procedure resulted 

 in a "slab" up to 5 cm thick approximately 75 cm above ground level; slots were located 

 at random with respect to cardinal direction (fig- 1) • Slots were used because radio- 

 graphing the entire tree would (1) superimpose images of broods from the near side upon 

 those on the far side, (2) require a much greater exposure time, and (3) result in radio- 

 graphs of low contrast. The slots were about 20 by 25 cm to accommodate Kodak AA Ready 

 Pack© film of that size, and were open only on one side in the larger trees to slow the 

 rate of tissue drying. In the smaller trees, the trunk was not large enough to keep one 

 side of the slot closed; consequently, slots were open on both sides. However, all slots 

 were sealed with caulking cord to slow the rate of drying between sample dates. 



Metal staples were placed in the corners of 15.2-cm^ areas to be radiographed. 

 Staples were visible on the radiographs and delinated areas from which population counts 

 would be made. During development of the beetle, radiographs were obtained October 14, 

 1969, June 2, 1970, and June 30, 1970. Plastic screen cages, 15.2 cm^, to which test 

 tubes had been attached, were stapled over the area delineated by the staples after 

 the last sample. Emerging insects were collected weekly from the test tubes, and 

 numbers, sexes, and sizes were recorded. 



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