BUREAU OF ENTOMOLOGY AND PLANT QUARANTINE 9 
season, and air temperatures were above normal early in the season. 
In contrast, the 1948 season, when Ips beetles were subsiding, was 
characterized by precipitation above normal during the spring months, 
soil moisture above normal, and temperatures well below normal for 
the entire season. The low temperatures in 1948 retarded Ips develop- 
ment so that only two and one-half generations were produced as com- 
pared with three and one-half generations in 1917. 
The importance of precipitation and soil moisture was further shown 
by a review of recorded Ips outbreaks during the last 25 years. Most 
of these epidemics occurred in years when the precipitation showed a 
cumulative monthly deficiency from January to June. 
The information that has been acquired through these investiga- 
tions is of value in applying preventive measures, such as timing of 
cuttings and treatment of slash, to avoid serious losses from Ips in- 
festations in reserve stands. 
Aerial Spraying Controls Spruce Budworms 
The outbreak of the spruce budworm that has been building up in 
Oregon and Washington continued to develop in 1948. About 1,000,- 
000 acres were known to be infested in 1947, chiefly in the Blue Moun- 
tains in the northeastern part of Oregon. In 1948 new centers of in- 
festation were found east of Mount Hood and near Eugene, bringing 
the total to nearly 1,500,000 acres. 
The infestations in the central and southern Rocky Mountain re- 
gions declined, except in northern New Mexico. Several areas of 
severe defoliation were reported in the northern Rocky Mountain 
region, but it has not been possible to determine how extensive they 
are. 
For the second year the budworm populations in northern New York 
declined noticeably. Birds played a conspicuous part in destroying 
the larvae. There was little change in Vermont and New Hampshire, 
but a marked increase in Maine. In the northern part of Aroostook 
County half the new balsam fir foliage in some stands was eaten in 
1948, which indicated the danger of outbreak proportions in 1949. 
An encouraging development was the highly successful control of the 
budworm in an aerial spraying experiment conducted in Oregon with 
the cooperation of the Oregon State Board of Forestry and the United 
States Forest Service. Test plots totaling 4,200 acres were sprayed 
during the last 10 days of the larval feeding period in July 1948. The 
spray was applied with an airplane and a helicopter at the rate of 1 
pound of DDT in 1 gallon of fuel oil per acre and gave between 95 
and 100 percent control. On the basis of these results, these agencies 
and timberland owners are cooperating with this Bureau in a control 
program aimed at spraying about 200,000 acres of the most valuable 
Douglas-fir and true-fir stands in 1949, 
Resistant Strains of Pines May Solve Weevil Problem in California 
Planting to -restock areas that were originally forested but were 
taken over by a heavy cover of brush after logging and fires has en- 
countered some striking failures. In northern California, where 
