To control this weevil spray the trees twice with 6 pounds of 50-percent DDT or 40-percent toxaphene wettable powder per 100 gallons of water. Make the first application when at least six weevils can be jarred onto a sheet on the ground beneath any tree known to have been infested in previous seasons, and make the second 10 to 14 days later. The first application will be needed sometime between the last week in July and the first week in September. If the soil is hard and dry, it will delay emergence of the weevils. If you are not equipped to spray, you can reduce weevil injury about 50 percent by jarring the limbs of the trees lightly and gathering the weevils on a sheet during the period of emergence. The dislodged weevils will remain quiet on the sheet long enough to be picked up and destroyed. Begin jarring about the last week in July and confine it to two or three trees until the first weevils appear. Then jar all trees at weekly intervals until about the middle of September, when egg laying will have been largely completed.

The butternut curculio[11] attacks native butternuts and introduced nuts of a similar type. It passes the winter as an adult in trash or other shelter it can find in the vicinity of nut trees. It is a small, hard-shelled, rough-backed snout beetle. Late in the spring it makes its way to the trees, and lays eggs in the young shoots. On hatching, the young larva penetrates into the young shoot or leaf stem or nut and feeds there, causing the leaf or nut to dry up and fall off. Upon completing development in the fallen leaf or nut, the mature larva enters the soil. After a month or so in the ground the adult emerges, feeds on the foliage for a while, and then enters hibernation. There is but one generation a year.

The black walnut curculio[12] is similar to the butternut curculio in seasonal history, but it attacks principally the fruit of the black walnut and butternut, apparently preferring the former.

The hickory nut curculio[13] is much like the preceding two species, but it attacks chiefly partly grown hickory nuts, causing a heavy dropping in midsummer.

The hickory shoot curculio[14] attacks chiefly the shoots of various kinds of hickory. The damage is seldom of much importance except to newly transplanted trees. On pecan it attacks the unfolding buds and shoots. Pecans most commonly attacked are those that are uncultivated or are adjacent to woodlands containing native pecan and hickory trees.

For many years these curculios have been controlled by spraying the trees soon after growth starts with lead arsenate, 2 pounds per 100 gallons, plus an equal amount of hydrated lime. One or two additional applications may be needed as new growth appears or as the nuts increase in size. Recent experimental work indicates that BHC or lindane may be more effective for controlling these insects. A spray containing 3 or 4 pounds of technical BHC (10-percent gamma) or 1-1/2 to 2 pounds of 25-percent lindane wettable powder per 100 gallons, applied when the buds show from 1/4 to 1 inch of green growth or when jarrings show adults are present, has given fairly good control.

Walnut Husk Maggot

The walnut husk maggot[15] attacks black and English walnuts, butternuts, and a few other nuts. The feeding of the larva, or maggot, in the husks impairs the quality of the kernels, discolors the shell, and often causes the shells to adhere to the nuts. It causes the most damage to English walnuts. This insect hibernates in the pupal stage in the ground. In midsummer it transforms to the adult fly stage, leaves the soil, and flies to the nut trees. After 1 to 3 weeks the flies lay eggs in the husks of the developing nuts. The eggs hatch in a week or 10 days, and the young maggots burrow within and throughout the husks of the nuts; they mature in the fall.

The walnut husk maggot can be controlled by spraying the trees with lead arsenate or cryolite the latter part of July and again 3 to 4 weeks later. Use 2 or 3 pounds of lead arsenate plus an equal quantity of hydrated lime or 3 pounds of cryolite per 100 gallons of water.

Filbert Moth