THE GRANARY WEEVIL 29 
The effect of a moderately low temperature is to prolong the life of 
the adult weevil. As already recorded by the writers (3), a few of 
the weevils placed in an ordinary refrigerator with a temperature 
that ranged between 50° and 60° F. lived for a period of 29 months. 
They were almost inactive at this temperature but fed occasionally. 
When kept at a temperature of 35° to 40° F. a few adults lived as 
long as 111 days, whereas at temperatures ranging from 40° to 45° F. 
adults survived for 105 days. A temperature of 30° to 35° F. proved 
fatal to adults of the granarv weevil after 73 days. A temperature 
of 25° to 30° F. killed all adults within 46 days. At 20° to 25° F. all 
adults were dead at the end of 33 days; at 15° to 20° F., at the end 
of 14 days; at 5° F., at the end of iy 2 hours. A constant tempera- 
ture of zero proved fatal to adults of the granary weevil at the end 
of an exposure of 5 hours. 
Twenty per cent of the eggs of the granary weevil survived an 
exposure to a constant temperature of 30° F. for 28 days. Larvae 
exposed to this temperature survived for 44 days. 
PARASITES 
The granarv weevil is attacked by several parasitic Hymenoptera 
while in the larval and pupal stages. The two most commonly 
observed in Xorth America are Aplastomorplia calandrae Howard and 
Chaetospila elegans Westw., while Lariopltagus distinguendus Forst. is 
apparently the most abundant parasite of the granary weevil in 
Europe. Goodrich (34), in 1921, wrote regarding parasites of beetles 
infesting grain. 
A predacious mite, Pediculoides ventricosus Newport, frequently 
attacks the egg, larva, and pupa of the granary weevil. 
CONTROL MEASURES 
Control measures consist chiefly in the use of heat, cold, and fumi- 
gants. The use of heat, in the ordinary grain heating and drying 
equipment on the market, seems not to be popular with gram dealers 
since grain is purchased by weight and heating results in the loss of 
moisture. A temperature of 118° F. to 120° F. for one hour or of 
130° F. for 30 minutes kills all stages of the weevil actually subjected 
to it. It should not be forgotten that the gram must" be heated 
sufficiently to allow the proper amount of heat to penetrate to the 
insects concealed within. In quarantine work the Federal Horti- 
cultural Board has found it advisable to require that corn entering 
this country from Mexico be subjected to a temperature of 200° F. 
for at least five minutes to insure freedom from insect pests. 
Dean (15) and Goodwin (33) have published on heat control. 
Carbon disulphide is the only fumigant at present hi general use hi 
the United States for killing weevils in gram hi bidk. When carbon 
disulphide is used at the rate of from 5 to 15 pounds per 1,000 bushels, 
according to the tightness of the crib, the granary weevil can be 
killed in all stages. Carbon tetrachloride alone and ethyl acetate- 
carbon tetrachloride mixture (47) vary hi effectiveness and must be 
used from two to four times as strong as carbon disulphide. The 
ethyl acetate-carbon tetrachloride mixture, however, is not entirely 
satisfactory to the gram trade on account of an odor which this mix- 
ture may leave. 
