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 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 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.






_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 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.






_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.






=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.



_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.






=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. For this reason poisons are

useless.






_Treatment._ About the only practicable remedy is to pick these insects

by hand. We can, however, protect our young plants by small nettings and

thus tide them over the most dangerous period of their lives. These bugs

greatly prefer the squash as food. You can therefore diminish their

attack on your melons, cucumbers, etc. by planting among the melons an

occasional squash plant as a "trap plant." Hand picking will be easier

on a few trap plants than over the whole field. A small board or large

leaf laid beside the young plant often furnishes night shelter for the

bugs. The bugs collected under the board may easily be killed every

morning.



=The Flea-Beetle.= The flea-beetle inflicts much damage on the potato,

tomato, eggplant, and other garden plants. The accompanying figure shows

the common striped flea-beetle which lives on the tomato. The larva of

this beetle lives inside of the leaves, mining its way through the leaf

in a real tunnel. Any substance disagreeable to the beetle, such as

plaster, soot, ashes, or tobacco, will repel its attacks on the garden

crops.




_a_, larva; _b_, adult. Lines on sides show real length of insects]



=The Weevil.= The weevil is commonly found among seeds. Its attacks are

serious, but the insect may easily be destroyed.



_Treatment._ Put the infected seeds in an air-tight box or bin, placing

on the top of the pile a dish containing carbon disulphide, a

tablespoonful to a bushel of seeds. The fumes of this substance are

heavy and will pass through the mass of seeds below and kill all the

weevils and other animals there. The bin should be closely covered with

canvas or heavy cloth to prevent the fumes from being carried away by

the air. Let the seeds remain thus from two to five days. Repeat the

treatment if any weevils are found alive. Fumigate when the temperature

is 70 deg. Fahrenheit or above. In cold weather or in a loose bin the

treatment is not successful. _Caution:_ Do not approach the bin with a

light, since the fumes of the chemical used are highly inflammable.



=The Hessian Fly.= The Hessian fly does more damage to the wheat crop

than all other insects combined, and probably ranks next to the chinch

bug as the second worst insect enemy of the farmer. It was probably

introduced into this country by the Hessian troops in the War of the

Revolution.






In autumn the insect lays its eggs in the leaves of the wheat. These

hatch into the larvae, which move down into the crown of the plant, where

they pass the winter. There they cause on the plant a slight gall

formation, which injures or kills the plant. In the spring adult flies

emerge and lay eggs. The larvae that hatch feed in the lower joints of

the growing wheat and prevent its proper growth. These larvae pupate and

remain as pupae in the wheat stubble during the summer. The fall brood of

flies appears shortly before the first heavy frost.



_Treatment._ Burn all stubble and trash during July and August. If the

fly is very bad, it is well to leave the stubble unusually high to

insure a rapid spread of the fire. Burn refuse from the

threshing-machine, since this often harbors many larvae or pupae. Follow

the burning by deep plowing, because the burning cannot reach the

insects that are in the base of the plants. Delay the fall planting

until time for heavy frosts.



=The Potato Beetle; Tobacco Worm.= The potato beetle, tobacco worm,

etc., are too well known to need description. Suffice it to say that no

good farmer will neglect to protect his crop from any pest that

threatens it.



The increase, owing to various causes, of insects, of fungi, of

bacterial diseases, makes a study of these pests, of their origin, and

of their prevention a necessary part of a successful farmer's training.

Tillage alone will no longer render orchard, vineyard, and garden

fruitful. Protection from every form of plant enemies must be added to

tillage.




One way of increasing the yield of fruit]



In dealing with plants, as with human beings, the great object should be

not the cure but the prevention of disease. If disease can be prevented,

it is far too costly to wait for it to develop and then to attempt its

cure. Men of science are studying the new forms of diseases and new

insects as fast as they appear. These men are finding ways of fighting

old and new enemies. Young people who expect to farm should early learn

to follow their advice.





=EXERCISE=



How does the squash bug resemble the plant louse? Is this a true

bug? Gather some eggs and watch the development of the insects in a

breeding-cage. Estimate the damage done to some crops by the

flea-beetle. What is the best method of prevention?






Do you know the large moth that is the mother of the tobacco worm?

You may often see her visiting the blossoms of the Jimson weed.

Some tobacco-growers cultivate a few of these weeds in a tobacco

field. In the blossom they place a little cobalt or "fly-stone" and

sirup. When the tobacco-worm moth visits this flower and sips the

poisoned nectar, she will of course lay no more troublesome eggs.





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