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Active control work was undertaken in northeastern Oregon in the fall of 1910, and was completed June 30, 1911. This work was done by the Bureau of Entomology, in cooperation with the Forest Service, with private owners, and with the General Land Office of the Department of the Interior. The preliminary reports indicate that 27,158 trees were treated at a cost of $33,180 to the Forest Service, and that 6,853 trees were treated at a cost of $2,806 to private owners. More than 100 men were engaged in the work during May and June. The results of this large control demonstration can not be known until the close of the present fiscal year, but it is believed that they will prove to be successful, and that the demonstration of methods and the training of men for control work will be of the greatest value in the future.
It is estimated that the timber saved as the direct result of control work in the Rocky Mountain region, under instructions from the Bureau of Entomology or according to its recommendations, represents a stumpage value of $2,000,000.
In my last report I called attention to the urgent need of the passage by Congress of a plant quarantine and inspection law, and showed that the United States is the only great power without a law to protect it from the introduction of plant diseases and insect pests. Practically all of the European and other foreign powers have such laws, as have also Canada and the other important English colonies. The United States has become a dumping ground for refuse stock, much of which comes to this country to be sold by auctioneers under the hammer. The better class of nursery stock is also often infested with insect pests or diseases which could be detected by proper inspection. More than half of the important insect pests of the fruit and farm products of this country were originally brought in on imported nursery stock, and these now occasion an annual tax of several hundred millions of dollars. The San Jose scale, the cotton boll weevil, the gipsy moth, and the brown-tail moth are instances of accidental importations, and the alfalfa weevil mentioned in a previous paragraph is another. Since my last report infested stock has been constantly coming in. The Bureau of Entomology has been notified by the customhouses and by the railroads when plants are received, and such arrangements as could be made for inspection at points of destination have been carried out. In most of the States there are efficient inspection laws and efficient inspectors. To exemplify the danger of the present condition of affairs, during the past year a careful inspection of the importations by the Department of Agriculture showed that more than 20 different pests had been brought to Washington from foreign countries on plants. Of course these were intercepted and destroyed, but the presence of 20 new pests whose capacities for crop destruction were undoubtedly very great affords the strongest possible argument for the passage of a National plant quarantine and inspection law. On three different occasions during the past year the gipsy moth has come in on imported stock consigned to different localities in the country.
Other important operations carried on by the bureau during the year may be briefly mentioned. The work against the cotton boll weevil has been continued. The weevil extended its range during the year into the State of Alabama. On the other hand, it was entirely absent from certain regions in northern Texas, where it was present last year. It also did no noticeable damage in Oklahoma. Studies of the parasites of the weevil were continued, and Texas parasites were introduced at two points in Louisiana. The work on tobacco insects was also continued. A notable discovery was made with regard to the so-called tobacco wireworm which indicates that it can be controlled by cultural means. It feeds naturally upon certain weeds and these weeds are eliminated by rotation of crops. In the study of sugar-cane insects new points of importance were ascertained. The Argentine ant and the cotton red spider work was continued. Demonstration work in the deciduous fruit regions in California, with remedies for the pear thrips, was carried on with excellent success, indicating that in prune orchards the yield from an acre treated according to the directions of the bureau reached a value of $367.93, where an untreated acre yielded only $6.65. Work upon the codling moth, plum curculio, Hessian fly, and the jointworm has been continued with success, and important advances have been made in methods of fighting insects affecting vegetable crops and stored products. Information on the subject of the house fly as a carrier of typhoid fever and on malarial mosquitoes has been published, and the study of the tick which transmits Rocky Mountain spotted fever has been completed. Further studies upon the cattle tick have been made, and an investigation of the possible influence of certain insects in the carriage of pellagra has been begun. The work on bee diseases has been continued.
BUREAU OF BIOLOGICAL SURVEY.
RATS AND THE PLAGUE.
The rat is one of the most destructive mammals known, and the vast losses it annually causes in the United States call for increased efforts to reduce its numbers and to exterminate it wherever possible. Moreover, the continuance of the bubonic plague in foreign countries. with which we have constant trade relations emphasizes the danger of the landing of plague-stricken rats from incoming ships, and renders imperative the need of perfecting means for the destruction of these vermin, now believed to be the chief means for disseminating this dread disease. During the past year experiments were continued to discover effective means of reducing the numbers of this pest, without the discovery, however, of methods superior to those recom. mended in Farmers' Bulletin 369. While poison and traps must continue to be the chief means of reducing the numbers of these mischievous rodents in public buildings, dwellings, stores, and warehouses, it can not be too strongly urged that preventive methods are vastly easier, much more effective, and in the long run cheaper. The rat-proofing of buildings, especially those in which foodstuffs are stored, should be insisted on as far as possible. This precaution, coupled with the withholding of food so as to reduce reproductory powers and make trapping and poisoning effective, will result in materially reducing the number of the pests and lessening the danger from them.
GROUND SQUIRRELS AND THE PLAGUE. Throughout much of the region west of the Mississippi River ground squirrels of many species abound. In past years much time and attention has been given to the study of the habits of these rodents and of methods of controlling them, since wherever found they are exceedingly destructive to farm crops, and in irrigation districts they do much damage by burrowing into embankments, thereby causing costly breaks. The spread of bubonic plague by rats to the ground squirrels of California, discovered by the Public Health and MarineHospital Service, is a matter of national importance, since there is danger not only that the disease may become endemic in that particular State but eventually, through the agency of other species of ground squirrels, spread to neighboring States and thus threaten the whole country. As yet plague germs have been found in only one other native rodent, the California wood rat, and in only one individual of that species. The destruction of a mammal so numerous and so widely distributed as the California ground squirrel is a very serious undertaking on account of the great cost involved, and yet safety from the plague can apparently be fully assured in no other way.
During the year careful experiments were made to discover, if possible, better and cheaper methods of poisoning ground squirrels, and a circular embodying the results of these experiments was published. The formulas in Biological Survey Circular 76 can be confidently recommended for cheapness and effectiveness. This circular has been widely distributed throughout California, with a view
to stimulating activity on the part of resident farmers and landowners generally in the work of ridding their lands of ground squirrels. When fully advised of the importance of the work, they have usually shown themselves ready to do their part. The present law of California, which requires the cooperation of all landowners in the work of exterminating ground squirrels, will, if fully enforced, go far toward providing a remedy, especially if the State, through county and other officials, arranges for furnishing poison or poisoned bait in necessary quantities to landowners at cost. By providing centers of distribution the poison can be supplied ready for use at comparatively low cost, which will greatly stimulate its use by farmers and others.
RELATION OF NATIVE MAMMALS TO SPOTTED FEVER.
The recently ascertained agency of certain of our native mammals in the transmission of diseases vastly increases the importance of a knowledge of the exact range of the species concerned and their habits. It is now known that the so-called spotted fever of the Rocky Mountain region is transmitted from certain native mammals to men through the agency of ticks. In its most virulent form this fever, fortunately, has a restricted range, being confined to a portion of Bitterroot Valley, western Montana; but in milder form it prevails in parts of Idaho, Wyoming, Utah, and Nevada, and probably elsewhere in the Rocky Mountain region. During the past year the Biological Survey, the Bureau of Entomology, and the Agricultural Experiment Station of Montana cooperated in a field and laboratory study of the agencies and manner by which the disease is transmitted to human beings. The work of the Biological Survey was chiefly confined to ascertaining the species of native mammals which carry ticks in any stage of development, since presumably one or more of these mammals is, if not the original, the chief source of infection.
A collection of the mammals of the valley and adjacent mountains was made and the ticks discovered were turned over to the assistants of the Bureau of Entomology for experiment and study. No fewer than 18 species of mammals were found to harbor fever ticks—proof of the great difficulty that must necessarily attend any attempts to exterminate all the wild hosts of the ticks over the region in which the fever prevails. The mammal found to be most frequently infested-possibly in this respect equaling all other wild mammals combined—is the common ground squirrel of the region (Citellus columbianus), which abounds over much of the valley. As a very important step in the suppression of the disease, a thoroughly organized campaign to exterminate this squirrel within the limits of the valley should be made. Such a campaign may be urged on the double ground of the public health and the advantage of the farmer, since this mammal is a very serious pest, not only in this particular valley, but wherever grain is sown in Washington, Oregon, Idaho, and Montana. In connection with a study of the local wild mammals, an assistant of the Biological Survey during the coming season will demonstrate to the people within the infested district the best method of exterminating this ground squirrel and other wild mammals that carry ticks. By means of State or county cooperation the small tickcarrying mammals of the western side of Bitterroot Valley, the area chiefly affected, could be exterminated at a comparatively small outlay of time and money.
Prairie dogs continue to be a scourge to farmers in many sections of the Middle West, and they exact heavy toll also from the stockmen by eating nutritious wild grasses which form the main reliance of range cattle. Their colonies sometimes number thousands of individuals, and as it requires only about 200 to consume the forage of a steer their colonies collectively are a heavy drain on both pasturage and crops. During the year many experiments have been made with a view to finding better methods of poisoning or otherwise destroying these animals without at the same time endangering the lives of valuable birds.
SILVER FOX INDUSTRY.
During the past year many inquiries have been received from various parts of the United States regarding the practicability of rearing the silver or black foxes for profit, and there is a steady demand for the Farmers' Bulletin on this subject. Interest in the business has no doubt been stimulated by the enormous prices obtained for skins, and even larger sums paid for first-class breeding animals. Efforts are being made to obtain all possible information as to the success of breeders who have engaged in the business with a view to issuing a supplemental report on the industry.
As a class, woodpeckers are among our most useful birds. They destroy numbers of noxious insects and lend effective aid to the preservation of forests, city shade trees, and fruit orchards. A bulletin on these birds was issued during the year, analyzing the food they eat, explaining the ways in which they are of value to the farmer, and indicating methods by which their number may be increased by the use of artificial nesting sites.