The pecan weevil, _Curculio caryae_ (Horn), is a late-season pest of
pecans in Texas. In years when severe infestations occur, this insect
may destroy a large portion of the pecan crop. The kernels are eaten out
by the larvae.
The adult is a brownish weevil which is about three-eighths inch long.
The female has a snout which is as long as the body; the male’s is
somewhat shorter.
The weevil appears in late August and early September. After the nut
kernels have hardened, the female chews a hole in the shell and deposits
her eggs in little pockets in the nuts. Creamy white grubs hatch from
the eggs and feed inside the nuts during the fall, attaining a length of
about three-fifths inch. When they reach maturity, the grubs chew a hole
about one-eighth inch in diameter in the shell, emerge from the nut and
drop to the ground in late fall and early winter. They burrow in the
soil to a depth of 4 to 12 inches and construct a cell. Some individuals
remain in the larval stage until the following fall when pupation
occurs. Other larvae do not transform to pupae until the succeeding
year. The adults appear during the summer, following pupation. The
entire life cycle requires from 2 to 3 years, most of this time being
spent in the soil.
[Illustration: Figure 11. Overwintered larva of the pecan nut
casebearer and characteristic injury to the developing shoots.]
_Control._—Frequently, certain trees in the orchard are more heavily
infested than others, since the adults usually do not go far from the
tree upon which they developed. The time at which insecticide
applications should be made to control this insect can be determined by
jarring the trees. Begin checking the first week in August. A large
sheet should be placed under a tree and the limbs jarred with a padded
pole. The weevils drop to the ground and remain motionless for a short
period, at which time they may be counted. When three or more weevils
are jarred from each tree, an application of spray containing 6 pounds
of 50 percent DDT wettable powder per 100 gallons of water should be
made[8].
[Illustration: Figure 12. Eggs of the first generation pecan nut
casebearer deposited on the tips of the young nuts.]