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while in the colder parts of the temperate zones they pass an · artificial or domestic existence. Not only do they occasion loss in weight, but the grain which they infest is unfit for consámption either by man or by most animals, and cannot be used profitably for seed. Three species of insects injuring stored wheat pass their adolescent stages within the kernel and are universally the most injurious forms. They are the rice and granary weevils and the Angoumois grain moth.
The Granary Weevil (Calandra granaria L.).-From the earliest times this weevil was known as an enemy to stored grain.
It became domesticated ages ago, lost the use of its wings, and is
strictly an indoor species. After the grain of wheat is punctured by the snout of the female, an egg is inserted. The resulting
larva makes room for its transforGRANARY WEEVIL, ADULT mations within the kernel by deAND LARVA. vouring the mealy interior.
The grains of most cereals are inhabited by a single larva, but several individuals can thrive in a kernel of maize. The length of
of the life cycle and the number of generations annually produced depend on season and climate. In southern United States there may be six or more generations per year. One pair is estimated to produce 6,000 descendants in a single year. Besides wheat, they attack all the other grains, and the chick-pea. The greatest damage is caused by the long-lived adults, which gnaw into the kernels for food and shelter.
The Rice Weevil (Calandra oryza L.) resembles the granary weevil in structure and habits. It differs from the granary weevil most essentially in having well developed wings, and consequently being often found in the field. It lays its eggs in the standing grain in the tropics, and in the extreme south of the United States, where it is erroneously called “black weevil.” It originated in India, was first found in rice, and is now established in most of the grain growing countries of the world.
The Angoumois Grain Moth (Sitotroga cerealella Ol.).—Since 1736 the injuries of this moth have been noticed in the province
of Angoumois, France, from which it received its name. In the United States it was noticed as early as 1728, and is often incorrectly called "fly weevil." It is widely spread and does incalculable damage in the southern states. It is rapidly. spreading, and where it has become established it is more injurious than the weevils, also attacking grain in the field as far north as central Pennsylvania.
The adult insect is often mistaken for a clothes moth. The eggs are deposited in standing grain and in the bin, singly or in
clusters of from 20 to 30. It requires at least 4 days for the eggs to hatch. The minute larvæ or caterpillars burrow into the kernels for food, and in 3 weeks or more they are matured. A silken cocoon is then spun within the kernel, the caterpillar
transforms to a pupa or chrysalis, and in GRAIN MOTH, ADULT
a few days the moth is again on the wing. in favorable weather the life cycle requires
5 weeks, and about 8 generations are produced annually in the south, where the insect breeds all winter.
The Mediterranean Flour Moth (Ephestia kuehniella Zell.). - The most important of all mill insects, it was comparatively unknown before 1877, when it was discovered in Germany. Its appearance was noticed in England in 1886, in Canada in 1889, in California in 1892, and in New York and Pennsylvania in 1895. While its range is yet limited, it is rapidly becoming distributed throughout the civilized world. The high and equable temperature maintained in modern mills has made the insect a formidable one, for this condition is highly favorable to its development.
Cylindrical silken tubes are formed by the caterpillars. They feed in these until full growth is attained, when a new silken domicile is formed. This becomes a cocoon in which occur the transformations to pupa and imago. In the warmest weather the life cycle is passed in 38 days. It is the habit of web spinning that renders the insect most injurious. Infested flour is soon felted together so as to clog the milling machinery, necessitating prolonged and costly stoppage. Flour or meal is preferred by the larva, but in the absence of these it attacks grain, and it flourishes on bran and all prepared cereal foods,
including crackers. In California it lives in the hives of honey bees.
Other Insect Enemies of stored wheat and its products are the Indian-meal moth, the meal snout-moth, the flour beetles, the meal worms and the grain beetles, which all occasion more or less damage. As warm weather favors the rapid breeding of all of these insects, the losses are enormous in the warmer climates. In the single state of Texas, the weevils alone are estimated to cause an annual loss to all grains of over $1,000,000.
FLOUR MOTH: а, ADULT; b, PUPA; C, LARVA.
Grain infested by the Angoumois grain moth may lose 40 per cent in weight and 75 per cent in farinaceous matter in 6 months.
Remedies.—Nearly all the insect enemies of stored grain have parasitic or predaceous enemies, or both. Mites and spiders prey on them, and several species of chalcis flies parasitize them. In the field they are preyed upon by nocturnal insects, birds and bats. Preventives and insecticidal remedies are known. Bisulphide of carbon (one pound to one ton of grain or to 1,000 cu. ft. of empty space) is the best insecticide, and naphthaline the most effective deterrent. Hydrocyanic-acid gas is used in fumigating mills to rid them of the Mediterranean flour moth. Perhaps the largest operation of this kind ever made was that of exterminating the moth in a six-story mill and its warehouse, cleaning house, and elevator, a total of over 3,000,000 cubic feet of space. A ton of cyanide of potash and
a ton and a half of sulphuric acid were used. Only two living worms and one moth were found, after the operation. It will perhaps require years for the mill again to become so infested as to need another treatment.
There is no weevil-proof wheat, but the small, hard-grained varieties are little troubled by insects. Advantageous practices for prevention are prompt threshing, inspecting, quarantining and disinfecting grain and everything connected with it; scrupulous cleanliness; construction of warehouses and mills to exclude insects; úse of improved machinery in mills; and storage in large bulk in a cool, dry, well-ventilated repository.
General Needs and Results.— With a better and increasing knowledge of farm management, of cultural system, and of the natural destroyers of wheat, it should require less than a generation of time to double the yield of wheat per acre. Thirty per cent is certainly a very reasonable figure to represent the average annual loss to wheat from attacks by natural agencies of destruction. One of the greatest immediate needs is to impress the wheat grower with the fact of this loss, for it is often little realized, especially when it results from invisible or unperceived instrumentalities of disease that secretly tread their way through field and plant over great areas of the wheat regions.
To minimize the effects of this great host of natural destroyers of wheat is a task that is profitable, certain of reward, and most imperative in its demands for attention. Since wheat is raised the world around in temperate zone climates, there is little danger of a world famine in wheat on account of their combined effects, for there is always a great probability that large areas will meet with normal conditions. An unusual coincidence of abnormal conditions over wide regions in different parts of the world may, however, raise the price of wheat and greatly change the magnitude and direction of the commercial streams of wheat over the entire world. Such a coincidence occurred in 1897, when the world's wheat crop was greatly reduced by drought in India and Australia, by wholesale destruction from insect pests in Argentina, by a wet harvest in France, and by inundation of the wheat fields of Austria-Hungary.
1 Chittenden, Some Insects Injurious to Stored Grain.
Insurance. While scientific and artificial means may lessen losses in many directions, the positive conditions in nature which make possible the operation of natural destroyers of wheat are quite beyond the sphere of man's dominion. In some cases the loss occasioned can be reduced to a small constant factor by means of insurance. This is especially true of loss by storm or fire. Hailstorms occur somewhere every season, but are generally of very limited area, frequently extending over but a few square miles of territory. Consequently a small premium affords protection. Available data concerning wheat insurance are not at all complete or satisfactory. The insurance of wheat in the field is embraced in the more general subject of the insurance of crops against destruction by liail and wind. Companies insuring crops frequently also insure other forms of property. In Scotland, hail insurance existed at least as early as 1780. The first known insurance against hailstorms in Germany is believed to have been in 1797, when the Mecklenburg Hail Insurance Association of Germany was founded. This company was still in existence in 1878. For the first 50 years of its career there was an average rate of 3.8 per cent of the amount insured. In 1812 anothier company was formed in Germany, having rates from 2.5 to 5 per cent. In 1888 there were 20 mutual and 5 stock hail insurance companies in Germany.
An attempt at hail insurance in France was first made in 1801, by M. Barrau, a philanthropic and enterprising man who was ahead of his time. He lost his fortune in the attempt, for it was thought to be an interference with the dealings of Providence; the government bureaus opposed the plan; and in 1809 the council of state suppressed the society. Permanent hail insurance in France dates from 1823. The average premium received during the subsequent 50 years was 1.05 per cent, while the average loss was 0.81 per cent. The first hail insurance in Austria was written in 1824, and in England in 1842, the latter including 34 acres of wheat at $58.40 per acre. The whole risk was $4304.66, and paid a premium of 1.6 per cent, and also a stamp tax of $5.41. In the United States the first hail insurance was by the Mutual Hail Insurance Company at Milwaukee, Wis., in 1850. It insured on the cash plan with premium notes. In 1878 it was doing business in 5 states.