. Forest insect and disease conditions in the United States 1979. Insect pests United States. eastern slope of the Bighorn Moun- tains. Of 1,400,000 acres of ponderosa pine type in the Colorado Front Range, an estimated 25 percent showed detectable infestations of mountain pine beetle. Within these infested areas, about 420,000 pines ( per acre) were attacked by the beetle in 1978, with 96,000 of these trees salvaged or chemically treated. In addition to these direct controls, preventive thinnings were made in intensively managed areas to help prevent future epidemics. Western spruce budwor
. Forest insect and disease conditions in the United States 1979. Insect pests United States. eastern slope of the Bighorn Moun- tains. Of 1,400,000 acres of ponderosa pine type in the Colorado Front Range, an estimated 25 percent showed detectable infestations of mountain pine beetle. Within these infested areas, about 420,000 pines ( per acre) were attacked by the beetle in 1978, with 96,000 of these trees salvaged or chemically treated. In addition to these direct controls, preventive thinnings were made in intensively managed areas to help prevent future epidemics. Western spruce budworm, Choristoneura occidentalis Free- man. The budworm defoliated about 930,000 acres of Douglas-fir and white fir in Colorado and continued to be a serious problem on the Front Range. The San Isabel and San Juan National Forests showed areas of light defoliation with moderate to heavy defoliation on the Pike, Arapaho, and Roosevelt National Forests. Front Range populations will remain static in 1980. Insuffi- cient data are available to predict 1980 population trends elsewhere in Colorado. On the Clarks Fork District of the Shoshone National Forest, light defoliation was reported. Top-kill was evident in pure Douglas-fir stands on the Arapaho National Forest in Colorado. Damage from budworm defoliation was negligible in other areas surveyed. Jack pine budworm, Choristoneura pin us Freeman. Jack pine budworm heavily defoliated about 1,100 acres of jack pine on the Bessey District of the Nebraska National Forest. Light to medium defoliation occurred on the remaining 1,300 acres of jack pine. Egg mass sampling in August indicated a potential for continued high budworm populations in 1980. Pine tip moths, Rhyacionia bushnelli (Busch), R. frustrana (Comstock), and neomexicana (Dyar). Pine tip moths damaged pon- derosa pine in the Black Hills and Shelterbelt plantings throughout the area east of the Missouri River. Nan- tucket pine tip moth populations in Kansas were apparently the lo
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