Orchard Insects





=The San Jose Scale.= The San Jose scale is one of the most dreaded

enemies of fruit trees. It is in fact an outlaw in many states. It is an

unlawful act to sell fruit trees affected by it. Fig. 150 shows a view

of a branch nearly covered with this pest. Although this scale is a very

minute animal, yet so rapidly does it multiply that it is very

dangerous to the tree. Never allow new trees to be brought into your

orchard until you feel certain that they are free from the San Jose

scale. If, however, it should in any way gain access to your orchard,

you can prevent its spreading by thorough spraying with what is known as

the lime-sulphur mixture. This mixture has long been used on the Pacific

coast as a remedy for various scale insects. When it was first tried in

other parts of the United States the results were not satisfactory and

its use was abandoned. However, later experiments with it have proved

that the mixture is thoroughly effective in killing this scale and that

it is perfectly harmless to the trees. Until the lime-sulphur mixture

proved to be successful the San Jose scale was a most dreaded nursery

and orchard foe. It was even thought necessary to destroy infected

trees. The lime-sulphur mixture and some other sulphur washes not only

kill the San Jose scale but are also useful in reducing fungous injury.







Magnified]



There are several ways of making the lime-sulphur mixture. It is

generally best to buy a prepared mixture from some trustworthy dealer.

If you find the scale on your trees, write to your state experiment

station for directions for combating it.




_a_, burrow of worm in apple; _b_, place where worm enters; _c_, place

where worm leaves; _e_, the larva; _d_, the pupa; _i_, the cocoon; _f_

and _g_, moths; _h_, magnified head of larva]



=The Codling Moth.= The codling moth attacks the apple and often causes

a loss of from twenty-five to seventy-five per cent of the crop. In the

state of New York this insect is causing an annual loss of about three

million dollars. The effect it has on the fruit is most clearly seen in

Fig. 152. The moth lays its egg upon the young leaves just after the

falling of the blossom. She flies on from apple to apple, depositing an

egg each time until from fifty to seventy-five eggs are deposited. The

larva, or "worm," soon hatches and eats its way into the apple. Many

affected apples ripen too soon and drop as "windfalls." Others remain on

the tree and become the common wormy apples so familiar to growers. The

larva that emerges from the windfalls moves generally to a tree, crawls

up the trunk, and spins its cocoon under a ridge in the bark. From the

cocoon the moth comes ready to start a new generation. The last

generation of the larvae spends the winter in the cocoon.




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.

Scrape all loose bark from the tree. Spray the tree with arsenate 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

arsenate of lead for a spray. Thus one spraying serves against both

fungi and insects.




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.






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

Spraying with arsenate 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.






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).




_a_, egg mass; _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.






_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

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.




_a_, eggs; _b_, cocoon; _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 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 larvae, too, since the pest spreads rapidly

from farm to farm. Regularly sprayed orchards are rarely troubled by

this pest.




_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, passing through the pupa

stage before it comes out to lay eggs for another generation.






_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 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?




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.




1, bugs on plant; 2, eggs; 3, young bug; 4 and 5, older bugs; 6,

long-winged bug; 7 and 8, short-winged bug]





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