ses the mouth is situated at a
greater distance from the eyes and other head appendages than is the
anal extremity of the insect. There are in the northern part of this
country two species which attack chestnuts, one which attacks
hickory-nuts, one which attacks hazel-nuts and about a dozen which
attack acorns. And here may be mentioned an interesting peculiarity of
the feeding habit which is decidedly to the advantage of the nut-grower.
Each species adheres closely to its own food plant. The hickory-nut
weevil does not attack hazel-nuts nor the hazel-nut weevil hickory-nuts.
None of the acorn-infesting species will seek for food in the nuts of
chestnut, hickory or hazel. Once the chestnut weevils are absent in a
locality, there is no chance that oak trees will serve as a means of
spreading the weevils back into the locality. So closely confined are
these weevils to their particular food plants that many of them
distinguish between the different species of oak and will oviposit only
in certain kinds of acorns.
All the different species resemble one another in both the adult and
larval stages. There is also a general similarity in their behavior. I
have recently discovered, however, a marked difference in the life
cycles of certain species. For example, the larger chestnut weevil and
the smaller chestnut weevil look alike, but they are decidedly unlike in
their development. The grubs of the larger weevil begin to leave the
nuts at about the time the nuts drop. They enter the soil to a depth of
several inches and fashion smooth-walled cells in which they remain
unchanged until the following summer. During June and July they
transform to pupae, and soon afterward to adults. In August they issue
from the ground and seek the trees where they collect around the burs
and begin to deposit eggs soon after the nut kernels start to form. This
life cycle is continued year after year. To forestall starvation of the
race in case of entire failure for a year of the chestnut crop, a few
individuals carry over the second winter in the ground and then issue as
beetles along with the one-year-old specimens. It is probable that a
small per cent of the insects may remain in the soil over three winters.
Thus does nature by unique arrangements safeguard the lives of even the
very small creatures.
The life cycle of the lesser weevil is quite different. The larvae of
this species leave the nuts somewhat later in the autumn than do those
of
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