1036 
Journal of Agricultural Research 
Vol. XXXI, No. 11 
of water under this pressure, this causes tne water content of all bodies compre¬ 
hended therein to cnange to a gaseous form, and thus all insects are killed. 
Brief notes on the effect on insects of a vacuum of 24 to 28 inches 
were given in a p ape r by the writers (1) at the Annual Convention 
of the American Warehousemen’s Association, held in Chicago in 
December, 1924. 
APPARATUS USED 
The.apparatus used by the writers in their experiments consisted 
of a concrete vault, 8 by 8 by 8 feet, and a large glass bell jar having 
a cubic content of approximately 825 cubic inches. The air was 
f nmped from these two containers by means of a dry vacuum pump, 
n the case of the large concrete vault a vacuum of 28 inches was 
obtained within a period of approximately one and a half hours. An 
automatic control then cut off the motor, the pump remaining idle 
until the vacuum fell to 24 inches, when the control device auto¬ 
matically started the motor again. The small amount of leakage 
that occurred allowed the vacuum to fall from 28 inches to 24 inches 
in from 4 to 6 hours. In the case of the bell jar a 29-inch vacuum was 
obtained within 30 seconds of the time the pump was started, but 
little leakage occurred and no control device was used; whenever nec¬ 
essary, the pump was started by hand. 
BELL-JAR EXPERIMENTS 
EXPERIMENT NO. 1 
In the first experiment specimens of 19 different species of insects 
affecting stored products were used. In some cases two or more 
stages of the insects were used, in others only the adults; in all cases 
from 10 to 50 specimens were used in each lot treated. The insects 
were subjected to a vacuum varying from 26 inches to 29 inches for 
periods of 1 day, 2 days, and 4 days, respectively. The temperature 
during the experimental period varied between 60° and 70° F. and the 
barometer reading for the period varied between 29.3 and 29.7 inches. 
Table I .—Effect of vacuum varying from 26 to 29 inches upon insects in bell jar 
of 825 cubic inches capacity 
Insect 
Killed in 1 day 
Killed in 2 days 
Killed in 4 days 
m 
bC 
fad 
W 
© 
c3 
> 
B 
© 
03 
P4 
3 
fX, 
m 
■8 
< 
to 
m 
tS 
W 
03 
03 
> 
b 
03 
a 
£ 
m 
+3 
3 
r d 
< 
tn 
bd 
bfi 
W 
© 
03 
> 
B 
© 
03 
a 
3 
fIn 
«3 
3 
Alphitobius piceus 01iv____ 
Ret. 
P. ct. 
P.ct. 
P. ct. 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
50 
100 
P.ct. 
P.ct. 
100 
100 
100 
100 
100 
100 
P. ct. 
P.ct. 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
P.ct. 
P. ct. 
100 
100 
100 
100 
100 
100 
P.ct. 
P.ct. 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
Anthrenus fasciatus Hbst 
50 
50 
100 
100 
100 
100 
100 
100 
100 
100 
Attag A ' ml F pififins Oliv 
Cryptolestes pusillus Schon 
Dermestes vulpinus Fab_ 
100 
100 
Ephestia kuebniella Zell 
100 
100 
Necrobiarufipes De Geer_ 
Oryzaephilus surinamensis 
Tj t __ _ _ _ _ 
100 
100 
100 
Plodia interpunctella Hbn. 
Silvanus gemellatus Duv,,_ 
100 
100 
100 
100 
100 
Sitophilns nryza L 
Sitophilus granarius L 
T 
_ 
_ 
Tp/nfibrin nbscnrns Fab 
100 
100 
100 
100 
100 
100 
100 
Tenebroides mauritanicus 
L. 
80 
50 
40 
100 
100 
100 
Tineola biselliella Hum.... 
Tinna j'lfillinnella Tj 
10 
100 
40 
100 
100 
100 
Tribolrum confusum Duv 
100 
100 
100 
100 
100 
100 
100 
100 
100 
100 
Tribolium ferrugineum Fab 
Trogoderma tarsale Melsh 
0 
20 
1 
