To de 
nil eons 
ermine this relationship expcrin 
out at the Berkeley laboratory. 
eits were recently carried 
Bark samples 
containing larval broods 
of the western pine beetle treated with varying classes of oil were 
exposed in special chambers in which the temperature, humidity, and 
air circulation were under control. 
weeks! exposure 
It was found chat from 1 to 3 
produced no effective killing at tem eratures below 
oU° F., regardless of quantity of oil used. 
of the larvae 
From 50 to 55 percent 
were killed with normal dosaze with 1 week of exposure 
at temperatures of 60° to 650° Ss at 70° to 90° F. high mortality oc- 
curred, ranging from S7 to 93 percent with light dosage to practically 
luv percent with Sei dosaze ‘f the oil. 
which had been kept for 3 weeks at temperatures below 5U° F. still re- 
teined sufficient. cao 
It was also found that bark 
produce hi¢h mortality when exposed to temper- 
atures within the killins range. This indicates that when bark is 
treated in the woods during pericds of cold weather it will retain suf- 
ficient oil in toxic quantities to insure 
temperatures occur later. 
avoreciable killing if warm 
aS Gevelovment cf western pine beetle larvae 
does not progress below temperatures of 50° F., the brocds in the 
treated bark will remo 
in dormant until temperatures reach the range in 
which the cil becomes effective. Regardless of the temperature condi- 
tions uncer which cil 
eniergence occurs. 
Mortality of 2 

sas due to cold.--Early in January the 

is a,plied, results become effective before 
Melrose Highlands, Mass., laboratury culiected egg clusters of 
rorthetria dispar L. from seven Massachusetts towns. to obtain infor- 
mation on the ECTS of the unusually Low 
ber on the hatching of the eges. The ey 
glass vials 5 
each was recorded, and when hatching was over 
ae 
& 
er 
in the ‘laboratory, the nun 
temperatures of late Decem- 
clusters were isolated in 
of larvae that issued from 
the unhetched eggs were 
exanined under oe microscope to determine the number that were fertile, 
the number infertile, the number containing living larvae of the egg 
parasite sanastatus Gisparis Jes and the number in which the para- 
J. EB. R. Solbrook ha conpleted this work and presents 
the information in the following nate form: 
site was dead. 

Town 
Clinton, liass. 
Concord, " 
Fitchburg, " 
Hyannis, " 
Middletvcro," 
Plymouth, * 
Saugus, n 



Fertile hee 
Lowest Egg Total eggs clusters 
temper- clus- fertile that giving cat- Anastatus 
ature ters eggs hetcned erpillars living 
OF. No. No. Percent Noe Percent 
~19 BU) Pi yRer 84.92 aU tigol 
24 a) 4,195 3.85 9.44 
~14 20 3, 168 puebG 12 36.66 
-~ 9 19 5 O52 78.62 20 90.55 
— 26 62.359 5.uUs 4 4,02 
~k1 20 10,937 34.47 2) 90.37 
-- 15 8,334 54.51 Le oe v4) 




