affectiny the Corn- Crops. 
99 
The warmer it is the oftener they pair, consequently the female 
lays her eggs every month when the heat is sufficiently great, 
but as soon as the mornings begin to be cold she ceases to lay ; 
and such is the vast multiplication of this insect sometimes in the 
granaries and magazines of France, that of a heap of corn, nothing 
but the husks is left, and all kinds of grain are acceptable to 
the Granary-weevil. 
From the moment of pairing until the lime when the weevil is 
hatched occupies about 40 or 45 days, from which it is evident that 
there are many generations in a year, which, as I have shown, 
multiply more rapidly in a hot country. From a very curious 
table, established upon the multiplication of the weevils, by adding 
together the number of each generation, the result obtained is 
a sum total of 6045 individuals proceeding from one pair only of 
weevils during a summer, namely, during five months, dated from 
the 15th of April to the 15th of September, when the ther- 
mometer is above 15° (nearly 66° Fahr.), and it never descends 
much lower in the southern provinces of France. As Olivier 
says, " One cannot be any longer astonished that enormous heaps 
of corn are sometimes so speedily devoured." As soon as the 
female weevil has been impregnated, she plunges deep into a 
heap of corn to lay and conceal her eggs immediately under the 
skin of the grains ; she makes a puncture where it is slightly 
raised in this part, and forms a little elevation which is scarcely 
perceptible. These holes are not perpendicular to the surface of 
the grains, but oblique, or even parallel, and stopped with a 
kind of gluten the colour of the corn. The female never lays 
more than one egg in each grain, which is not long in hatching, 
and, when lodged in the grain, is perfectly secure from changes 
in the atmosphere, because the excrement that it makes seems 
to close the opening by which it entered, and even when the corn 
is removed it is not incommoded by any shaking it may undergo. 
It will be observed that the weevils are not found on the surface, 
but some inches deep in the corn -heaps ; it is there that they live, 
very often couple, and that the females lay their eggs. Moreover, 
on looking at a heap of corn, one cannot detect the operations 
of these insects in the grains where they are lodged ; they have 
the same form, the same appearance, they seem to be as large, 
as firm as those which are not attacked : it is only by the weight 
that they can be detected, and on throwing a handful from a heap 
into water, the diseased grains will float. So long as the weather 
remains hot the weevils do not quit the corn-heaps they have 
invaded, unless they are obliged to abandon them by stirring the 
corn with shovels or passing it through a sieve. When the 
mornings begin to be cool, all the weevils, young and old, 
abandon the corn-heaps, which are no longer a retreat sufficiently 
H 2 
