SWEET-POTATO WEEVIL ERADICATION AND CONTROL.

Following an urgent request, an emergency fund of $30,000 was made available about March 1 for an investigation of the sweetpotato_weevil in the States of Florida, Georgia, Alabama, Mississippi, Louisiana, and Texas, which might lead to its eradication and control. This has made possible a preliminary farm-to-farm survey of all outlying infested territory, definitely establishing the boundaries of infestation. A series of large-scale experiments in control have been undertaken at field stations in Texas, Mississippi, and Florida, and demonstration eradication projects have been initiated in portions of Florida, Georgia, Mississippi, and Alabama, the close survey accomplished having established the feasibility of operations for that purpose.

An educational campaign by inspectors has already been productive of much benefit and has reduced materially the number of infested farms in Georgia, Alabama, and Mississippi; indeed, it seems probable that the completion of another season's work may find the sweet-potato crop of the least infested of these States nearly weevil free.

Experiments with heat curing of sweet potatoes have shown the possibility of securing a mortality of 95 per cent of weevils in storage houses by carrying the tubers at a temperature of 115° F. for eight days. In badly infested districts in Texas, where weevil injury is frequently 50 per cent, losses have been reduced to less than 10 per cent by the timely application of arsenical sprays.

Life-history investigations have brought forward many interesting facts regarding this weevil which can be applied the coming season to excellent advantage. Good progress has been made in a survey of the wild food plants of the pest. On the whole, the beginning of the fiscal year 1919 finds the bureau well equipped to conduct a most effective campaign against this pest during the coming season.

OTHER INSECTS OF POTATO, TOMATO, AND ALLIED PLANTS.

The potato aphis, which was an unexpected pest in 1917, reappeared in still greater numbers in many regions in the early summer of 1918. It attacked both tomato and potato, and occurred along the Atlantic coast from Maryland and Virginia to New England and to a lesser extent westward to Ohio, Indiana, Illinois, Michigan, and Wiscon

In Maryland it was controlled by nicotine sulphate used at double the strength generally advised for plant-lice. This doubling was necessitated by the greater resistance of the pest and by the unwillingness of the farmers to make a second spraying, on account of the scarcity of labor and appropriate spraying machinery. A still larger dosage, namely, one-half pint of nicotine sulphate to 50 gallons of water, was found desirable in New Jersey and Massachusetts.

The spinach aphis caused considerable loss to potato, tomato, cabbage, turnip, radish, beets, lettuce, and other truck crops. It covered practically the same territory and succumbed to the same remedies.

The potato flea-beetle, the three-lined potato beetle, and the potato fruitworm, as well as the common stalk-borer, were numerous and received careful consideration.

INSECTS AFFECTING GROWING BEANS AND PEAS.

An investigation of the bean ladybird-an insect which is to the bean crop of Colorado, New Mexico, and neighboring States what the Colorado potato beetle was to the potato crop in earlier yearswas undertaken, and the results are available for publication. Additional experiments, however, are necessary for the control of this insect in order to lessen damage to the crop by the means of control themselves.

The pea aphis has been studied in California, as well as a pea moth which has been introduced during the year into Wisconsin, and two species of borers which affect especially Lima beans, one in the Southern States and the other in the Pacific region. Enormous areas in Lima beans and other beans were planted this year in southern California, and there has been a severe and unusual outbreak of the corn earworm upon the bean pods in that part of the country, necessitating careful studies of the conditions which have brought about the damage in the hope of preventing it another year.

OTHER TRUCK-CROP INSECTS.

The problem of the control of the onion thrips has been solved, and the department is now able to prescribe practically new methods of treatment which give excellent results. Some progress has been made in the control of the onion maggot by the use of sweetened sodium arsenate and arsenite in the destruction of the adult flies while depositing their eggs.

In the same way insects injurious to crucifers, such as the cabbage aphis, the false turnip aphis, and the harlequin cabbage bug, have been studied. The last-named pest, ordinarily an important one throughout the South, was largely controlled by the cold winter of

1918.

Work on insects injurious to strawberry, blackberry, raspberry, and related plants of the rose family has been continued in several States, and good results have been accomplished in the line of control of the leaf-rollers by arsenical spraying. A saving of at least 50 per cent was made in experiments in Iowa, and in Kansas a single spraying resulted in destroying two-thirds of the pests.

Investigations of insects as agents in the transmission and overwintering of the disease of cucurbit vegetables known as "mosaic" have been continued in Indiana and Wisconsin. Hundreds of individual insects were used in hibernation experiments, and about 100 experiments in control by insecticides are now under way.

The principal investigations of the insects affecting sugar beets have led toward the solution of the problem presented by the annual damage from the curly-top disease. It has been shown that a leafhopper is the agent responsible for the transmission of this disease, and studies of the life history and economy of the insect carrier have been nearly completed. These have led to experiments in the time of planting which have yielded results of such value that their application to commercial plantings will probably insure a paying crop in infested regions.

SOUTHERN FIELD-CROP INSECT INVESTIGATIONS.

Dr. W. D. Hunter has been in charge of these investigations, as formerly.

COTTON-BOLL WEEVIL KILLED BY POISON.-One of the most striking achievements of the bureau culminated during the year in the announcement of the value of powdered lead arsenate or calcium arsenate against the cotton-boll weevil. After years of experimentation the bureau is now able to announce that the weevil can be killed during the summer months by dusting the cotton with either of these poisons at the rate of 5 pounds per acre, with three to five applications at weekly intervals. The poisoning, to be most effective, should be done between 4 p. m. and 9 a. m., and the powder should be applied by means of a rotary dust gun or by power machinery. A special power machine has been developed which will cover nearly 200 acres per day. The cost of treatment is about $1 per acre for one application. Distinct gains in yield of from 250 to 1,000 pounds of seed cotton have been obtained. It is hoped that the application of this discovery will greatly increase the yield per acre of cotton, one of the most important crops of the Nation.

OTHER COTTON INSECTS.-Other work on cotton insects, as indicated in the last annual report, has been carried on at Tallulah, La., Madison, Fla., and El Centro, Cal., the recent developments of cotton in the last locality, in the Imperial Valley, necessitating careful watch for cotton pests.

Research work on the pink bollworm of cotton in the Laguna district of Mexico has been carried on by experts of the bureau detailed to the Federal Horticultural Board, and will be mentioned in the report of the board.

OTHER SOUTHERN FIELD-CROP INSECTS.-On account of the extension of sugar-cane culture in southwestern Texas, a laboratory has been opened at Brownsville for the investigation of sugar-cane insects. The investigations on tobacco insects, mentioned in the last report, have been continued.

The demands of the War Department for great quantities of castor oil led to very extensive planting of castor beans under contract in various southern States. Early in the season complaints began to come in of insect injury to these plantations, and the bureau has given especial attention to the control of these pests..

INSECTS AFFECTING THE HEALTH OF MAN AND ANIMALS.

With the beginning of the war, very elaborate tabulations and card indexes of the relationships of insects to the health of man and animals were prepared. This information has been placed at the service of the War Department and has enabled the bureau to give prompt service in many emergency cases. A close contact has been maintained with the sanitary officers, so that the bureau has been able to render service in the solution of certain camp problems.

Acting in cooperation with the National Research Council and the War Department, a study of the body louse was taken up and in

vestigations have been made of all remedies proposed against the louse. Especial researches have also been undertaken in the search for new lines of treatment. Results of all tests are immediately communicated to the office of the Surgeon General of the War Department.

The chief of the bureau has been made chairman of the subsection of medical entomology of the National Research Council, and in this way all questions that arise are officially handled.

The work on insects affecting domestic animals, as outlined in the last annual report, has been continued. The insects frequenting packing houses and abattoirs have been under observation. Traps of different kinds have been experimented with, and the other lines of work indicated in the last annual report have been followed up.

INVESTIGATIONS OF INSECTS AFFECTING FOREST RESOURCES.

The work of the branch of Forest Insects, under the supervision of Dr. A. D. Hopkins, has been concentrated during the year on subjects which have a direct or indirect bearing on war-time needs.

Early in the year a conference was held with representatives of the branches of the War and Navy Departments, Shipping Board, etc., who are responsible for the supplies drawn from the forest resources of the country. The object of this conference was to offer the services of the bureau and explain how it could help through special investigations and advice toward preventing serious losses of forest resources from damage by wood and bark boring insects.

Recent investigations of logging and manufacturing operations in Mississippi to meet the demand for ash oars, handles, and other supplies, required by the war service, showed that one company had lost more than 1,000,000 feet of ash logs through failure to provide for prompt utilization after the trees were cut and thus prevent the attack of the destructive ash-wood borers.

There is a continued reduction of the heretofore serious losses of seasoned ash and other hardwood sap material from powder post, due to the more general adoption of the methods advised by the bureau. This has been accomplished largely through the adoption of methods of management by the manufacturers and shippers with little or no additional cost.

By far the most extensive insect-control reconnaissance that has been carried out to date is the "California survey," which was completed during the year. This was organized as a cooperative project in which a number of California lumber companies, the Forest Service, and the Bureau of Entomology were engaged. The general supervision of the survey was assigned to the assistant forest entomologist, Mr. J. M. Miller, who has charge of the Pacific slope field station.

The territory covered consisted of the pine belt along the western flank of the Sierra Nevada Mountains between the American and Kern Rivers. The results of this survey showed that the loss in 1917 from tree-killing beetles on the 1,682,000 acres covered was approximately 27,000,000 feet of merchantable timber with a stumpage value of $60,000. If the recommendations of this bureau are adopted by the Forest Service and private owners and properly carried out, it is certain that a large percentage of this annual loss can be prevented,

and that through the application of the percentage principle of control it is entirely practicable to do so at a comparatively small cost.

In the Southwest, where the mesquite furnishes the only local supply of fuel, fence posts, etc., serious losses are suffered each year from wood-boring insects. Large quantities of mesquite are used for fuel at the Army cantonments, rendering the problem of especial interest in this connection. In order to determine a method of conserving the resources supplied by the mesquite, a special field station was established near Tucson, Ariz., at which mesquite has been cut every two weeks since October, 1917. The results of this experiment so far have been most gratifying in showing that mesquite cut in November and December and piled in loose ricks is comparatively free from damage, while that cut during the other months is seriously affected and in some cases its value is entirely destroyed.

The black locust has come into prominence on account of its value in supplying the best pins used in the construction of wooden ships. Heretofore it has not been practicable to grow this tree commercially on account of the damage to the tree and wood by the locust borer, but recent experiments have shown conclusively that it can be protected from the borer by spraying the young trees with a poisoned liquid and by a more practical method of providing a dense shade in the plantations by the use of some quick-growing shade-producing plant between the rows.

In connection with the pressing need of an increased food supply, Dr. Hopkins volunteered his services for the investigation of periodical farm practice with special reference to the application of his bioclimatic law of latitude, longitude, and altitude as a guide to the best time and period each season to do the work. This law, which has been worked out in its relation to research and practice in entomology, was believed by him, as suggested in the report of the Entomologist for the fiscal year 1917, to be equally applicable to research and practice in agriculture. Therefore much of his time during the year was devoted to a study of the application of the law to the predetermination of the safest and best time to sow winter wheat at any place in the United States where the conditions are favorable for its profitable growth.

The results of the investigations as set forth in his paper, "Periodical Events and Natural Law as Guides to Agricultural Research and Practice," published as Supplement 9 of the Monthly Weather Review, seem to have proved the practicability of the application and to have introduced a new line of attack for all problems relating to periodical farm practice, and seem to have a promise of ultimate results of special value toward increasing the food supply and the general advancement of agriculture.

TROPICAL AND SUBTROPICAL FRUIT INSECT INVESTIGATIONS.

This branch of the bureau's investigations is under the charge of the assistant chief of the bureau, Mr. C. L. Marlatt.

INVESTIGATIONS OF INSECTS AFFECTING CITRUS FRUITS IN CALIFORNIA. Work in control of the two important mealybug enemies of citrus trees has been continued during the year and has resulted in notable success. The means now recommended by the department are