32 BULLETIN 1303, U. S. DEPARTMENT OF AGRICULTURE 
varying from G1.5° to 68.5° F., the pupal stage lasted from 10 to 
16 days. 
The developmental period from egg to adult may be completed in 
28 days, which, with a preoviposition period of 7 days, makes pos- 
sible a life cycle from eg«j to egg of 35 days. The normal egg-to- 
adult cycle in summer is between 30 and 40 days, to which should 
be added, in securing the egg-to-egg cycle, a period varying from G 
days in midsummer to 14S days if the adult happens to emerge dur- 
ing the fall and hibernate as adult. There may be three or four 
generations a year in the vicinity of Washington, D. C. 
The granary weevil is very resistant to low temperatures. Prac- 
tically all of a large number of adults refrigerated at 30° to 35° F. 
were found alive after one month, and a few survived for 73 days. 
Adults exposed to a constant temperature of 15° F. survived only for 
9 days, to 5° F. for 7}4 hours, and to zero Fahrenheit for 5 hours. 
Of eggs exposed to 30° F. for 28 days, 20 per cent survived. A few 
lame survived refrigeration at 30° F. for 44 days. 
The granary weevil is not very resistant to high temperatures. Ex- 
posure for a few hours to 115° F. will kill all stages, and all stages 
are killed within one hour when exposed to 118° to 120° F. Moder- 
ately high temperatures are also fatal if maintained for any length 
of time. At 95° F. four-fifths of the adults died on the fifth day of 
exposure, and a few lived 9 days, and one for 13 days; little or no 
feeding occurred and no eggs were laid. Eggs incubated at 95° F. 
failed to hatch, and larvae exposed to this temperature did not com- 
plete their development. 
The granary weevil in both larval and pupal stages is attacked by 
several hymenopterous parasites. Although these may become very 
numerous at times, they can not be depended upon for effective con- 
trol, which can be secured only by heating the grain to a tempera- 
ture of 125° F. or above, or by fumigation with standard effective 
fumigants. 
LITERATURE CITED 
(1) Back, E. A. 
1919. Conserving corn from weevils in the Gulf Coast States. U. S. 
Dept. Agr., Farmers' Bui. 1029, 36 pp., illus. 
(2) and Cotton, R. T. 
1922. Stored-grain pests. U. S. Dept. Agr., Farmers' Bui. 1260, 47 pp., 
illus. 
(3) 
1924. Relative resistance of the rice weevil, Sitophilus oryza L., and the 
granary weevil, S. granarius L., to high and low temperatures. 
In U. S. Dept. Agr., Jour. Agr. Research, vol. 28, pp. 1043- 
1044. 
(4) Chapman, R. X. 
1921. Insects infesting stored food products. Tniv. Minn. Agr. Exp. 
Sta. Bui. 198, 76 pp., illus. 
(5) 
1923. The possibility of transmitting a Calendra infestation from wheat 
to macaroni thru the processes of milling and manufacturing. 
/// Jour. Econ. Ent., vol. 16. pp. 341-348, illus. 
(6) Chittenden, F. H. 
1895. The more important insects injurious to ptored grain. In U. S. 
Dept. Agr. Yearbook 1894, pp. 277-294 illus. 
(7) 
(8) 
1896. Sonic insects injurious to stored grain. U. S. Dept. Agr., Farmers' 
Bui. 45, 24 pp., illus. 
1896. Insects affecting cereals and other dry vegetable foods. In U. S. 
Dept. Agr., Div. Ent. Bui. 4, n. B., pp. 112-130, illus. 
