Numerous stands of western larch, Larix occidentalis, on the St. Joe, Coeur d'Alene, and Kaniksu National Forests, Idaho, show signs of gradual deterioration following repeated defoliation by larch casebearer, Coleophora Zaricella Hbn. (Tunnock et al. 1969). Stand deterioration can occur after 4 years of continued heavy defoliation. The main symptom...
The larch casebearer, Coleophora laricella (Hubner) was first reported attacking western larch, Larix occidentalis, in Idaho in 1957 (Denton, 1958), 71 years after its introduction into Massachusetts from Europe. The apparent successful regulation of this insect in the eastern U.S. by introduced parasites prompted biological control attempts in the West....
Aerial surveys of the Nezperce National Forest in Idaho revealed 138,692 acres of aerially visible top kill and tree mortality due to repeated defoliation by western spruce budworm, Choristoneura occidentalis Freeman.
A small ground sample indicates that up to 47 percent of the grand fir volume was affected by top...
The larch casebearer Coleophora laricella (Hbn.) is now established throughout all western larch stands in Region 1. Population levels have begun to fluctuate in some of the older infested stands; however, it is still on the increase in more recently invaded territory. During the past 2 years work was begun...
An attempt was made in January 1971 to relate the numbers of hibernating western spruce budworm larvae on a square foot of bark surface with subsequent shoot damage on Douglas-fir and grand fir in northern Idaho.
Twenty-six plots sampled in January were also sampled in April to determine
if larval...