THE GRANARY WEEVIL 23 
30° F., and then removed to a warm temperature, hatched 32 days 
after deposition. Although 4 days is the minimum period observed 
by the writers, eggs have been observed to hatch in 5 days after- 
deposition when the temperature for the incubation period ranged 
from a mean of 68.7° F. (90° F. maximum, 46° F. minimum) 
and of 82.8° F. (95° F. maximum, 68° F. minimum). 
Although the data of Table 4 indicate that the length of the incu- 
bation period is from 4 to 15 days under more normal conditions and 
may be extended over a period of at least 32 days during colder 
weather, there are dealers in grain who firmly believe that eggs are 
capable of passing through a very long period of development, and 
that they are capable of a suspended development when temperature 
conditions are unfavorable to growth, only later to resume normal 
development upon the return of favorable temperature conditions. 
It has been found that the female weevils do not begin to mate and 
lay eggs until the temperature is from 61° to 63° F., and that even at 
these temperatures eggs are not deposited every day. It is not until 
the temperature has risen to 66° to 68° F. that mating and oviposition 
occur daily. It would appear from observations that eggs are not 
deposited at temperatures below the minimum at which they can start 
development. Should the temperature drop to below 50° to 55° F. 
for a considerable period, there is every reason to believe that egg 
development is suspended indefinitely and that eggs perish for lack 
of warmth. No eggs were observed to hatch after the temperature 
of the grain had reached 95° F. or above. 
THE LARVA 
When the embryo is fully developed, its undulating movements 
cause a rupture of the thin eggshell, and the young larva emerges to 
find an abundance of food ready at hand. It immediately begins to 
feed, burrowing through the tissues of the seed, forming a winding 
tunnel that increases in size with the growth of the larva. The 
tunnel is often close to the surface of the seed, and in corn, particu- 
larly, the progress of the larva is sometimes distinctly visible through 
the seed coat (fig. 4). 
FOOD OF THE LARVA 
The larva breeds in all the common grains, such as corn (fig. 4), 
oats, barley (fig. 2), rye, wheat (fig. 3), kafir, buckwheat, millet, and 
also in chick-peas (fig. 9). It is said to breed in acorns, chestnuts, 
and sunflower seeds, although Strachov-Koltchin states that he failed 
to get them to breed in sunflower seeds. It is unable to breed in loose 
farinaceous material, such as flour and semolina used in making 
macaroni, but breeds readily in manufactured products of cereals, 
such as macaroni (fig. 5), noodles, and probably other similar prod- 
ucts, and in milled cereals that have become badly caked from excess 
moisture. The larva feeds on all parts of the seed, but prefers the 
soft starchy portion. As it bores and tunnels through the seed it 
thrusts the borings and frass behind it, so that the mine it lea\ es 
behind is always filled. It has been found that larva 1 can feed in 
grain with a moisture content as low as 8 per cent, although feeding 
undoubtedly progresses more normally when the moisture content is 
about 14 to 16 per cent. 
