Agriculture for Beginners, Daniel Harvey Hill [best ereader under 100 .txt] 📗
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Fig. 156. The Cankerworm
Fowls in the orchard do good by capturing the larvæ before they can burrow, while hogs will destroy the fallen fruit before the larvæ 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).
Fig. 157. The Spring Cankerworm
a, egg mass; b, egg, magnified;
c, larva; d, female moth; e, male moth
Fig. 158. Eggs of the
Fall Cankerworm
In early summer the larvæ 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 larvæ 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.
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 larvæ leads up the trunk. We must obstruct this highway so that no crawling creature may pass. 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 pass will be entangled. Printer's ink will do very well, or you can buy either dendrolene or tanglefoot.
Fig. 159. Apple-Tree Tent Caterpillar
a, eggs; b, cocoon; c, caterpillar
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
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 passes the winter in the egg state securely fastened on the twigs as shown in Fig. 159, a.
Treatment. There are three principal methods, (1) Destroy the eggs. The egg masses are readily seen in winter and may easily be collected and burned by boys. The chickadee eats great quantities 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 larvæ, too, since the pest spreads rapidly from farm to farm. Regularly sprayed orchards are rarely troubled by this pest.
The Twig Girdler. The twig girdler lays her eggs in the twigs of pear, pecan, apple, and other trees. It is necessary that the larvæ 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 larvæ 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, passing through the pupa stage before it comes out to lay eggs for another generation.
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 larvæ.
EXERCISE
How many apples per hundred do you find injured by the codling moth? Collect some cocoons 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 woodpecker hunting for these same cocoons? Can you find cocoons that have been emptied by this bird? Estimate how many he considers a day's ration. How many apples does he thus save?
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.
SECTION XXXIII. GARDEN AND FIELD INSECTSTHE 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
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 butterflies 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 butterfly, c shows several examples of the caterpillar, and d shows the pupa case. In the pupa stage the insects pass 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 pupæ 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.
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 larvæ. 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 grasses, 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.
Fig. 164. Cabbage Worms and Butterflies
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 grass, 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, Washington, for bulletins on the chinch bug. Other methods of prevention are to be found in these bulletins.
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.
The plant louse gives off a sweetish fluid of which some ants are very fond. You may often see the ants stroking these lice to induce them to give off a freer flow of the "honey dew." This is really a method of milking. However friendly and useful these "cows" may be to the ant, they are enemies to man in destroying so many of his plants.
Fig. 166. A Cheap Spraying Outfit
Treatment. These are sucking insects. Poisons therefore do not avail. They may be killed by spraying with kerosene emulsion or a strong soap solution or with tobacco water. Lice on cabbages are easily killed by a mixture of one pound of lye soap in four gallons of warm water.
Fig. 167. A Squash Bug
The Squash Bug. The squash bug does its greatest damage to young plants. To such its attack is often fatal. On larger plants single leaves may die. This insect is a serious enemy to a crop and is particularly difficult to get rid of, since it belongs to the class of sucking insects, not to the biting insects.
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