Agriculture for Beginners Part 16

[Ill.u.s.tration: FIG. 153. SPRAYING THE ORCHARD BRINGS LUSCIOUS FRUIT The picture in the corner at the top shows the right time to spray for codling moth]

_Treatment._ Destroy orchard trash which may serve as a winter home.

Sc.r.a.pe all loose bark from the tree. Spray the tree with a.r.s.enate of lead as soon as the flowers fall. A former method of fighting this pest was as follows: bands of burlap four inches wide tied around the tree furnished a hiding-place for larvae that came from windfalls or crawled from wormy apples on the tree. The larvae caught under the bands were killed every five or six days. We know now, however, that a thorough spraying just after the blossoms fall kills the worms and renders the bands unnecessary. Furthermore, spraying prevents wormy apples, while banding does not. Follow the first spraying by a second two weeks later.

It is best to use lime-sulphur mixture or the Bordeaux mixture with a.r.s.enate of lead for a spray. Thus one spraying serves against both fungi and insects.

[Ill.u.s.tration: FIG. 154. PLUM CURCULIO Larva, pupa, adult, and mark on the fruit. (Enlarged)]

=The Plum Curculio.= The plum curculio, sometimes called the plum weevil, is a little creature about one fifth of an inch long. In spite of its small size the curculio does, if neglected, great damage to our fruit crop. It injures peaches, plums, and cherries by stinging the fruit as soon as it is formed. The word "stinging" when applied to insects--- and this case is no exception--means piercing the object with the egg-layer (ovipositor) and depositing the egg. Some insects occasionally use the ovipositor merely for defense. The curculio has an especially interesting method of laying her egg. First she digs a hole, in which she places the egg and pushes it well down. Then with her snout she makes a crescent-shaped cut in the skin of the plum, around the egg.

This mark is shown in Fig. 154. As this peculiar cut is followed by a flow of gum, you will always be able to recognize the work of the curculio. Having finished with one plum, this industrious worker makes her way to other plums until her eggs are all laid. The maggotlike larva soon hatches, burrows through the fruit, and causes it to drop before ripening. The larva then enters the ground to a depth of several inches.

There it becomes a pupa, and later, as a mature beetle, emerges and winters in cracks and crevices.

[Ill.u.s.tration: FIG. 155. LEAF GALLS OF PHYLLOXERA ON CLINTON GRAPE LEAF]

_Treatment._ Burn orchard trash which may serve as winter quarters.

Spraying with a.r.s.enate of lead, using two pounds of the mixture to fifty gallons of water, is the only successful treatment for the curculio. For plums and peaches, spray first when the fruit is free from the calyx caps, or dried flower-buds. Repeat the spraying two weeks later. For late peaches spray a third time two weeks after the second spraying.

This poisonous spray will kill the beetles while they are feeding or cutting holes in which to lay their eggs.

[Ill.u.s.tration: FIG. 156. THE CANKERWORM]

Fowls in the orchard do good by capturing the larvae before they can burrow, while hogs will destroy the fallen fruit before the larvae can escape.

=The Grape Phylloxera.= The grape phylloxera is a serious pest. You have no doubt seen its galls upon the grape leaf. These galls are caused by a small louse, the phylloxera. Each gall contains a female, which soon fills the gall with eggs. These hatch into more females, which emerge and form new galls, and so the phylloxera spreads (see Fig. 155).

_Treatment._ The Clinton grape is most liable to injury from this pest.

Hence it is better to grow other more resistant kinds. Sometimes the lice attack the roots of the grape vines. In many sections where irrigation is practiced the grape rows are flooded when the lice are thickest. The water drowns the lice and does no harm to the vines.

=The Cankerworm.= The cankerworm is the larva of a moth. Because of its peculiar mode of crawling, by looping its body, it is often called the looping worm or measuring worm (Fig. 157, _c_). These worms are such greedy eaters that in a short time they can so cut the leaves of an orchard as to give it a scorched appearance. Such an attack practically destroys the crop and does lasting injury to the tree. The worms are green or brown and are striped lengthwise. If the tree is jarred, the worm has a peculiar habit of dropping toward the ground on a silken thread of its own making (Fig. 156).

[Ill.u.s.tration: FIG. 157. THE SPRING CANKERWORM _a_, egg ma.s.s; _b_, egg, magnified; _c_, larva; _d_, female moth; _e_, male moth]

In early summer the larvae burrow within the earth and pupate there; later they emerge as adults (Fig. 157, _d_ and _e_). You observe the peculiar difference between the wingless female, _d_, and the winged male, _e_. It is the habit of this wingless female to crawl up the trunk of some near-by tree in order to deposit her eggs upon the twigs. These eggs (shown at _a_ and _b_) hatch into the greedy larvae that do so much damage to our orchards.

Nearly all the common birds feed freely upon the cankerworm, and benefit the orchard in so doing. The chickadee is perhaps the most useful. A recent writer is very positive that each chickadee will devour on an average thirty female cankerworm moths a day; and that if the average number of eggs laid by each female is one hundred and eighty-five, one chickadee would thus destroy in one day five thousand five hundred and fifty eggs, and, in the twenty-five days in which the cankerworm moths crawl up the tree, would rid the orchard of one hundred and thirty-eight thousand seven hundred and fifty. These birds also eat immense numbers of cankerworm eggs before they hatch into worms.

[Ill.u.s.tration: FIG. 158. EGGS OF THE FALL CANKERWORM]

_Treatment._ The inability of the female to fly gives us an easy way to prevent the larval offspring from getting to the foliage of our trees, for we know that the only highway open to her or her larvae leads up the trunk. We must obstruct this highway so that no crawling creature may pa.s.s. This is readily done by smoothing the bark and fitting close to it a band of paper, and making sure that it is tight enough to prevent anything from crawling underneath. Then smear over the paper something so sticky that any moth or larva that attempts to pa.s.s will be entangled. Printer's ink will do very well, or you can buy either dendrolene or tanglefoot.

[Ill.u.s.tration: FIG. 159. APPLE-TREE TENT CATERPILLAR _a_, eggs; _b_, coc.o.o.n; _c_, caterpillar]

Encourage the chickadee and all other birds, except the English sparrow, to stay in your orchard. This is easily done by feeding and protecting them in their times of need.

=The Apple-Tree Tent Caterpillar.= The apple-tree tent caterpillar is a larva so well known that you only need to be told how to guard against it. The mother of this caterpillar is a reddish moth. This insect pa.s.ses the winter in the egg state securely fastened on the twigs as shown in Fig. 159, _a_.

_Treatment._ There are three princ.i.p.al methods, (1) Destroy the eggs.

The egg ma.s.ses are readily seen in winter and may easily be collected and burned by boys. The chickadee eats great quant.i.ties of these eggs.

(2) With torches burn the nests at dusk when all the worms are within.

You must be very careful in burning or you will harm the young branches with their tender bark. (3) Encourage the residence of birds. Urge your neighbors to make war on the larvae, too, since the pest spreads rapidly from farm to farm. Regularly sprayed orchards are rarely troubled by this pest.

[Ill.u.s.tration: FIG. 160. THE TWIG GIRDLER AT ITS DESTRUCTIVE WORK _a_, the girdler; _b_, the egg-hole; _c_, the groove cut by girdler; _e_, the egg]

=The Twig Girdler.= The twig girdler lays her eggs in the twigs of pear, pecan, apple, and other trees. It is necessary that the larvae develop in dead wood. This the mother provides by girdling the twig so deeply that it will die and fall to the ground.

_Treatment._ Since the larvae spend the winter in the dead twigs, burn these twigs in autumn or early spring and thus destroy the pest.

=The Peach-Tree Borer.= In Fig. 161 you see the effect of the peach-tree borer's activity. These borers often girdle and thereby kill a tree.

Fig. 162 shows the adult state of the insect. The eggs are laid on peach or plum trees near the ground. As soon as the larva emerges, it bores into the bark and remains there for months, pa.s.sing through the pupa stage before it comes out to lay eggs for another generation.

[Ill.u.s.tration: FIG. 161. BORER SIGNS AROUND BASE OF PEACH TREE]

_Treatment._ If there are only a few trees in the orchard, digging the worms out with a knife is the best way of destroying them. You can know of the borer's presence by the exuding gum often seen on the tree-trunk.

If you pile earth around the roots early in the spring and remove it in the late fall, the winter freezing and thawing will kill many of the larvae.

=EXERCISE=

How many apples per hundred do you find injured by the codling moth? Collect some coc.o.o.ns from a pear or an apple tree in winter, place in a breeding-cage, and watch for the moths that come out. Do you ever see the woodp.e.c.k.e.r hunting for these same coc.o.o.ns? Can you find coc.o.o.ns that have been emptied by this bird? Estimate how many he considers a day's ration. How many apples does he thus save?

[Ill.u.s.tration: FIG. 162. PEACH-TREE BORERS, MALE AND FEMALE Female with broad yellow band across abdomen]

Watch the curculio lay her eggs in the plums, peaches, or cherries.

What per cent of fruit is thus injured? Estimate the damage. Let the school offer a prize for the greatest number of tent-caterpillar eggs. Watch such trees as the apple, the wild and the cultivated cherry, the oak, and many others.

Make a collection of insects injurious to orchard fruits, showing in each case the whole life history of the insect, that is, eggs, larva, pupa, and the mature insects.

[Ill.u.s.tration: THE TROUBLESOME CHINCH BUG (ENLARGED) 1, bugs on plant; 2, eggs; 3, young bug; 4 and 5, older bugs; 6, long-winged bug; 7 and 8, short-winged bug]

SECTION x.x.xIII. GARDEN AND FIELD INSECTS

=The Cabbage Worm.= The cabbage worm of the early spring garden is a familiar object, but you may not know that the innocent-looking little white b.u.t.terflies hovering about the cabbage patch are laying eggs which are soon to hatch and make the dreaded cabbage worms. In Fig. 164 _a_ and _b_ show the common cabbage b.u.t.terfly, _c_ shows several examples of the caterpillar, and _d_ shows the pupa case. In the pupa stage the insects pa.s.s the winter among the remains of old plants or in near-by fences or in weeds or bushes. Cleaning up and burning all trash will destroy many pupae and thus prevent many cabbage worms. In Fig. 164 _e_ and _f_ show the moth and zebra caterpillar; _g_ represents a moth which is the parent of the small green worm shown at _h_. This worm is a common foe of the cabbage plant.

[Ill.u.s.tration: FIG. 163. THE DREADED CHINCH BUG]

_Treatment._ Birds aid in the destruction of this pest. Paris green mixed with air-slaked lime will also kill many larvae. After the cabbage has headed, it is very difficult to destroy the worm, but pyrethrum insect powder used freely is helpful.

=The Chinch Bug.= The chinch bug, attacking as it does such important crops as wheat, corn, and gra.s.ses, is a well-known pest. It probably causes more money loss than any other garden or field enemy. In Orange county, North Carolina, farmers were once obliged to suspend wheat-growing for two years on account of the chinch bug. In one year in the state of Illinois this bug caused a loss of four million dollars.

[Ill.u.s.tration: FIG. 164. CABBAGE WORMS AND b.u.t.tERFLIES]

_Treatment._ Unfortunately we cannot prevent all of the damage done by chinch bugs, but we can diminish it somewhat by good clean agriculture.

Destroy the winter homes of the insect by burning dry gra.s.s, leaves, and rubbish in fields and fence rows. Although the insect has wings, it seldom or never uses them, usually traveling on foot; therefore a deep furrow around the field to be protected will hinder or stop the progress of an invasion. The bugs fall into the bottom of the furrow, and may there be killed by dragging a log up and down the furrow. Write to the Division of Entomology, Was.h.i.+ngton, for bulletins on the chinch bug.

Other methods of prevention are to be found in these bulletins.

[Ill.u.s.tration: FIG. 165. A PLANT LOUSE COLONY]

=The Plant Louse.= The plant louse is very small, but it multiplies with very great rapidity. During the summer the young are born alive, and it is only toward fall that eggs are laid. The individuals that hatch from eggs are generally wingless females, and their young, born alive, are both winged and wingless. The winged forms fly to other plants and start new colonies. Plant lice mature in from eight to fourteen days.