The Douglas-fir beetle, Dendroctonus pseudotsugae Hopk., has caused extensive tree mortality for the third consecutive year in the North Fork Clearwater River drainage in northern Idaho. In 1972, the infestation encompassed about 494,080 acres of commercial forest lands in this drainage. It was estimated from a tw-stage aerial photo-ground survey that 240,00 trees were killed during the 3-year period 1970-72, resulting in a loss of about 109 MMBF of Douglas-fir sawtimber. Infestation levels are expected to decline in 1973, but significant tree mortality is expected in Localized infestation centers.
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