BROAD-NOSED GRAIN WEEVIL. fi 
LARVAL HABITS. 
The larva or grub bores straight down into the grain at first and 
is rarely found near the surface. It tunnels around rather aimlessly, 
fillimg up the passageway behind it with frass and borings. It 
usually remains in the soft parts of the grain. 
PREPUPAL STAGE. 
When fully grown the larva prepares for the change to the pupa 
or resting stage. It uses the end of its burrow for a pupal chamber, 
packing the frass and borings at the ends into a compact mass. 
The larva lengthens out and becomes sluggish, assuming the pre- 
pupal form. This stage lasts for one day in warm weather and two 
days in winter. 
PUPAL STAGE. 
The pupal stage lasts for a period of five days during warm weather 
when the temperature ranges from 65° to 99° F., with a mean of 
about 81°. As with the other stages, cold weather has the effect of 
lengthening the period. Table 3 contains data showing the varying 
length of this stage at different times of the year. 
NUMBER OF MALES AND FEMALES. 
Of several hundred weevils reared in the laboratory and of large 
numbers collected in the field, the males and females were about 
equalinnumbers. The males and females closely resemble each other 
in outward appearance and can not be differentiated without the 
ald of a magnifying glass. 
As with many other weevils the beak of the female differs slightly 
from that of the male and affords a ready means of distinguishing 
between the two sexes. The beak or proboscis of the female is approx- 
imately equal in width for its entire length and is longer and more 
slender than that of the male. The beak of the male is slightly 
enlarged at the tip and narrows gradually toward the base. 
COPULATION. 
Copulation occurs within a few days after emergence and is re- 
peated at intervals. It occurs chiefly at night. These weevils are 
rarely to be seen in copula during the day. 
Unfertilized females have been observed to lay eggs but rarely. 
None of these eggs have been found to hatch, so it is doubtful 
whether unfertilized females are capable of laying fertile eggs. 
LIFE CYCLE. 
The period from egg to adult during warm weather averages about 
30 days, which with an average preoviposition period of 22 days gives 
