Part 15 (1/2)
THE OAK PRUNER (_Elaphidion villosum_): Sometimes[M] pecan twigs, when smartly bent, will snap off with a clean, square cut across the branches, as if they were hollow-gla.s.s tubes, breaking at cracked or weakened places. An examination of such a broken stem shows ”that its woody part, with the exception of a few fibers and the bark, has been cut across as if with a saw by a soft, yellowish-white grub, which can often be found in a burrow in the severed part. Since the uncut bark is the chief support left for the branch, any stiff wind or even its own weight will break it off as soon as it has become deadened. * * * * * *
”The adult is a longicorn beetle, of slender, cylindrical form, over one-half inch in length and about one-eighth of an inch in width. It is of a dull, black color, tinged with brown on the wing covers, especially toward their tips. The underside of the body and legs are chestnut colored. Over all parts of the body can be found short, grayish hairs. Some small, gray spots on the wing-covers and a whitish dot on each side of the thorax are formed by dense collections of gray hairs at these points.
Coa.r.s.e, round punctures are thickly sprinkled over the upper surface of the thorax and wing-covers.
”The larva, when grown, is about three-fifths of an inch long, tapering backwards from the neck. The body is divided by deep grooves into twelve rings or segments. There are three pairs of feet. The color is yellowish-white, the front of the head being blackish. Probably, about midsummer, with a possible variation of two mouths in each direction from this date, the parent beetle deposits her eggs, preferably on a small twig of the preceding year's growth. Upon hatching, the young larva commences to eat the tender wood just beneath the bark, and later enters the center of the twig and works toward its base.
In this manner it works its way into the main limb, which may be of considerable size, and feeds within it for a period of about three years. The burrow thus becomes several inches in length, in many cases. Just before transforming to pupae some, but not all, of the larvae, cut the wood for the purpose of dropping the branches, as before described. Limbs in which the immature larvae are working often break off with ragged end when bent with the hand.
”* * * Pick up and burn all fallen branches. Similar attention should be given nearby oak and hickory limbs, which have fallen.”
THE PECAN TREE BORER (_Sesia scitula_): The moth of this insect is clear-winged and closely resembles the moth of the peach tree borer.
Little is known of its life-history.
”It[N] is probable that the eggs are deposited by the female moth on the bark of a tree near a fresh wound. For example, near newly set buds. The eggs hatch and the larvae bore into the bark, and there live for a time, eating out the soft inner-bark and tender wood. It is certain that the borers live in these situations the over winter and change to pupae in the spring, from which the moths emerge in April. The moths I reared appeared April 3rd, 4th and 6th. The pupae are in coc.o.o.ns, just under the bark. The coc.o.o.ns are made from excrement and bits of bark that have been fastened together with silk similar to the coc.o.o.ns of the peach tree borer. Whether these moths, that emerge in the spring, lay eggs and produce a brood in the summer, that in turn develops a fall brood of larvae, I am unable to say.”
”The[O] young borer is apt to gain entrance to the sapwood through some wound in the bark, such as a graft-union, and here it feeds, sometimes completely girdling the sapwood above and below the wound. It is said to prefer to attack buds that have been budded on old, large trees. As a general rule the burrows ascend the tree in a spiral about the trunk, so complete girdling is unusual, but growth sometime ceases above the groove, new limbs being shot out from below.”
The only satisfactory means of controlling this pest is to go carefully over the tree and dig out the borers. The trees should be examined from time to time in order to keep them free from borers.
INSECTS ATTACKING THE FRUIT.
THE PECAN WEEVIL (_Balantinus caryae_): In some localities considerable damage has been caused by the pecan weevil. The insect is a small, brownish-black snout beetle, somewhat less than one-half inch in length.
The proboscis or snout is slender and as long as the body. With this proboscis the beetle bores a very small hole through the husk and sh.e.l.l of the immature pecan to the kernel, and at the bottom deposits an egg.
This egg hatches into a larva, which feeds upon the kernel of the nut.
In autumn the larvae, when full grown, bore holes through the sh.e.l.ls of the pecan and enter the ground in which they pa.s.s the winter. The next season they emerge from the earth as fully-matured insects, and about the month of August deposit their eggs in the nuts.
After the harvesting of the crop the hogs should be allowed to feed under trees in which the weevil is present, so as to devour any infested nuts which may have been left on the ground. Poultry may also be of a.s.sistance in destroying the insects after they have entered the ground to pupate. It is probable that the larvae in the nuts may be destroyed by fumigating with carbon bi-sulphide. The nuts should be placed in a tight box, and one-half pound for each five hundred cubic feet of s.p.a.ce used, allowing them to remain for forty-eight hours.
THE HICKORY SHUCK WORM (_Grapholitha caryana_): Sometimes pecan nuts are attacked, as they approach maturity, by a small, white caterpillar, which mines its way through the shucks of the nuts. This caterpillar is the hickory shuck worm, the larva of a small moth.
But little is known of its life-history, and until more is known of its habits, the best advice that can be given is to gather and destroy the infested nuts by burning them.
FOOTNOTES:
[M] Gossard.
[N] Hedrick. (See index of literature).
[O] Gossard. (See index of literature).
PART VI.