Economic Loss from Insects.--The money value of crops, forest trees, stored
foods, and other material destroyed annually by insects is beyond belief.
It is estimated that they get one tenth of the country's crops, at the
lowest estimate a matter of some $300,000,000 yearly. "The common schools
of the country cost in 1902 the sum of $235,000,000, and all higher
institutions of learning cost less than $50,000,000, making the total cost
of education in the United States considerably less than the farmers lost
from insect ravages.
"Furthermore, the yearly losses from insect ravages
aggregate nearly twice as much as it costs to maintain our
army and navy; more than twice the loss by fire; twice the
capital invested in manufacturing agricultural implements;
and nearly three times the estimated value of the products
of all the fruit orchards, vineyards, and small fruit farms
in the country."--SLINGERLAND.
The total yearly value of all farm and forest products in New York is
perhaps $150,000,000, and the one tenth that the insects get is worth
$15,000,000.
Insects which damage Garden and Other Crops.--The grasshoppers and the
larvae of various moths do considerable harm here, especially the "cabbage
worm," the cutworm, a feeder on all kinds of garden truck, and the corn
worm, a pest on corn, cotton, tomatoes, peas, and beans.
Among the beetles which are found in gardens is the potato beetle, which
destroys the potato plant. This beetle formerly lived in Mexico upon a wild
plant of the same family as the potato, and came north upon the
introduction of the potato into Colorado, evidently preferring cultivated
forms to wild forms of this family.
[Illustration: Cotton-boll weevil. _a_, larva; _b_, pupa; _c_, adult.
Enlarged about four times. (Photographed by Davison.)]
The one beetle doing by far the greatest harm in this country is the
cotton-boll weevil. Imported from Mexico, since 1892 it has spread over
eastern Texas and into Louisiana. The beetle lays its eggs in the young
cotton fruit or boll, and the larvae feed upon the substance within the
boll. It is estimated that if unchecked this pest would destroy yearly one
half of the cotton crop, causing a loss of $250,000,000. Fortunately, the
United States Department of Agriculture is at work on the problem, and,
while it has not found any way of exterminating the beetle as yet, it has
been found that, by planting more hardy varieties of cotton, the crop
matures earlier and ripens before the weevils have increased in sufficient
numbers to destroy the crop (see page 126).
The bugs are among our most destructive insects. The most familiar examples
of our garden pests are the squash bug; the chinch bug, which yearly does
damage estimated at $20,000,000, by sucking the juice from the leaves of
grain; and the plant lice, or aphids. One, living on the grape, yearly
destroys immense numbers of vines in the vineyards of France, Germany, and
California.
[Illustration: Female tussock moth which has just emerged from the cocoon
at the left, upon which it has deposited over two hundred eggs. (Photograph
by Davison.)]
[Illustration: Caterpillar of tussock moth. (Photograph by Davison.)]
Insects which harm Fruit and Forest Trees.--Great damage is annually done
trees by the larvae of moths. Massachusetts has already spent over
$3,000,000 in trying to exterminate the imported gypsy moth. The codling
moth, which bores into apples and pears, is estimated to ruin yearly
$3,000,000 worth of fruit in New York alone, which is by no means the most
important apple region of the United States. Among these pests, the most
important to the dweller in a large city is the tussock moth, which
destroys our shade trees. The caterpillar may easily be recognized by its
hairy, tufted red head. The eggs are laid on the bark of shade trees in
what look like masses of foam. (See figure on page 215.) By collecting and
burning the egg masses in the fall, we may save many shade trees the
following year.
The larvae of some moths damage the trees by boring into the wood of the
tree on which they live. Such are the peach, apple, and other fruit-tree
borers common in our orchards. Many beetle larvae also live in trees and
kill annually thousands of forest and shade trees. The hickory borer
threatens to kill all the hickory trees in the Eastern states.
Among the bugs most destructive to trees are the scale insect and the plant
lice. The San Jose scale, a native of China, was introduced into the fruit
groves of California about 1870 and has spread all over the country. A
ladybird beetle, which has also been imported, is the most effective agent
in keeping this pest in check.
Insects of the House or Storehouse.--Weevils are the greatest pests,
frequently ruining tons of stored corn, wheat, and other cereals. Roaches
will eat almost anything, even clothing; they are especially fond of all
kinds of breadstuffs. The carpet beetle is a recognized foe of the
housekeeper, the larvae feeding upon all sorts of woolen material. The larvae
of the clothes moth do an immense amount of damage, especially to stored
clothing. Fleas, lice, and particularly bedbugs are among man's personal
foes. Besides being unpleasant they are believed to be disease carriers and
as such should be exterminated.[31]
Footnote 31: Directions for the treatment of these pests may
be found in pamphlets issued by the U. S. Department of
Agriculture.
Food of Starfish.--Starfish are enormously destructive to young clams and
oysters, as the following evidence, collected by Professor A. D. Mead, of
Brown University, shows. A single starfish was confined in an aquarium with
fifty-six young clams. The largest clam was about the length of one arm of
the starfish, the smallest about ten millimeters in length. In six days
every clam in the aquarium was devoured. Hundreds of thousands of dollars'
damage is done annually to the oysters in Connecticut alone by the ravages
of starfish. During the breeding season of the clam and oyster the boats
dredge up tons of starfish which are thrown on shore to die or to be used
as fertilizer.