REPORT OF THE ENTOMOLOGIST.

UNITED STATES DEPARTMENT OF AGRICULTURE,

BUREAU OF ENTOMOLOGY, Washington, D. C., August 24, 1916.

SIR: I submit herewith a report of the work of the Bureau of Entomology for the fiscal year ended June 30, 1916.

Hon. D. F. HOUSTON,

L. O. HOWARD,

Entomologist and Chief of Bureau.

Secretary of Agriculture.

WORK ON THE GIPSY MOTH AND BROWN-TAIL MOTH.

The work on the gipsy and brown-tail moths was continued as formerly under the direction of Mr. A. F. Burgess. Many improvements in methods have been made as the result of experiments which have been conducted. A large number of parasites have been colonized in areas where they were not known to have occurred previously, and the results of the work on the entire project have been very satisfactory.

STATES RELATIONS AND COOPERATION.-Cooperation with the officials charged with moth work in the various States infested has been maintained throughout the year with good results. This cooperative work has prevented duplication of effort and has enabled each of the States and the bureau to accomplish much more work than would otherwise have been done. Numerous conferences have been held, and more uniform methods have resulted from these meetings.

PROGRESS OF THE GIPSY-MOTH WORK IN NEW ENGLAND.-Scouting work has been carried on in the towns along and just outside the infested border. Two hundred and fourteen towns in all have been carefully examined during the year. Over 12,000 miles of roadways and 24,000 acres of woodland have been examined. The heavy snows of last winter, however, rather seriously hampered work of this kind. In the woodlands the high elevations have been most carefully searched, as from these places the insect is most likely to be spread. The result of the scouting has been that the gipsy moth has been found in 10 towns in New Hampshire, 2 in Vermont, 2 in Massachusetts, and 1 in Connecticut where it was not known to exist previously. On the other hand, in 2 towns in New Hampshire, 2 in

Vermont, 4 in Massachusetts, and 3 in Connecticut the insect has apparently been exterminated. There is therefore a net increase of only 4 infested towns, which is a much smaller number than has been found in previous years. All of the infestations discovered in these towns have been carefully treated, and a large amount of creosoting, banding, and spraying has been done in towns immediately inside the border. Approximately 35 tons of arsenate of lead were used this year, and spraying was done with 13 high-power sprayers. The purchase during the year of a motor-truck sprayer made it possible to treat a much larger area more economically than heretofore. This machine will do the work of four horse-drawn machines.

There has been a very noticeable decrease in the number of insects in the towns along the border which were treated last year. Considerable work has been done throughout several tiers of towns inside the border in order to prevent continued spread throughout adjoining areas, and here the results have been very satisfactory. The small colonies formerly existing in Great Barrington and Lenox have been thoroughly scouted, but no moths have been found.

PROGRESS OF THE WORK IN OHIO.-The site of the former colony at Bratenahl, a suburb of Cleveland, Ohio, has been thoroughly examined, and as a precautionary measure the trees were sprayed again during the summer by the State nursery inspector. No infestation has been found on this site during the year, and it is believed that the insect has been exterminated.

PROGRESS OF THE WORK IN NEW JERSEY.-The site of the former colony at Rutherford, N. J., has received careful attention, and no indication of the presence of the moth has been found.

PROGRESS OF THE WORK IN NEW YORK.-During the year the entire park system of Rochester has been examined, as it was feared that the moths might have gained a foothold from nursery stock which has been shipped in during the last few years, but no evidence of the insect was found. In the colony which was located at North Castle a large amount of work has been done, but only eight egg clusters have been found, all of these being outside the area which was sprayed last year. Work is being continued at this point in cooperation with the department of agriculture of the State of New York, and the entire area and a surrounding strip have been sprayed this year. Work will be carried on, and it is believed that the insect can be stamped out.

BROWN-TAIL MOTH SITUATION.-The severity of the brown-tail moth infestation has steadily decreased, and the insect is by no means as abundant as it was the previous year. The various lighthouses along the coast of Connecticut and Long Island have been examined, but no migrating moths have been found. Fewer moths have been found on trains coming from infested regions during the season when the moths are flying than in any year since this work has been begun. This indicates quite clearly that the moth is not spreading into new territory, and the conditions in the territory known to be infested showed marked improvement and in many of the towns where this insect once caused much damage and annoyance it has done little injury during the year.

QUARANTINE WORK.-The inspection of nursery stock and forest and quarry products has been kept up throughout the year, and in accordance with the new regulations of the Federal Horticultural Board Christmas trees and greens were allowed to be shipped from the infested area after inspection. Shipments of quarantined products numbering 37,444 have been examined and passed, 664 of which were found infested and were required to be treated before shipment was allowed. On these latter shipments 11,159 specimens of the gipsy moth in all stages, except the adult form, and 517 browntail moth webs were found and destroyed.

As a result of the effective work which is being carried on along the outside border of the quarantined area, a change has been made in the inspection regulations so that shipments that are being sent into slightly infested territory must be inspected hereafter the same as those that pass outside the quarantined area. This regulation will assist in preventing reinfestation of territory which is being treated and, it is hoped, will hasten the time when the quarantine may be lifted from some of the towns along the outer border.

SILVICULTURAL WORK.-The sample plats under observation to secure data on the best method of thinning infested woodland have been examined from time to time during the year, and much new information has been secured. Final results from these plats can not be expected for several years. Considerable information has been gathered concerning the best methods of utilizing the wood products grown in the infested area, as it would stimulate the elimination of favored food plants of the caterpillar if more profitable markets could be found.

EXPERIMENTAL WORK.-During the year a large number of experiments have been conducted with several kinds of tree-banding material in the effort to reduce the expense of this process. The study of the gipsy moth as a cranberry pest has been continued, special attention having been paid to the dispersion of small caterpillars over the bogs on account of the wind drift. Studies have been made of the increase of the gipsy moth under normal field conditions, the relation of disease and parasites, and the effect of defoliation on different species of trees. An investigation has also been begun to determine the reason why gipsy-moth egg clusters in several localities failed to hatch.

PARASITE AND DISEASE WORK.-The thorough investigation of the so-called wilt disease of the gipsy moth has been continued, and many facts concerning the obscure causative organism of this disease have been secured. Apparently this organism, which is an important factor in reducing the number of gipsy moths, attacks many native caterpillars.

The colonization of parasites imported from Europe and Japan has been continued during the fall of 1915. One hundred and fiftynine colonies of Japanese egg parasites known as Schedius kuvanae were liberated in 28 towns in Massachusetts and 11 in New Hamp shire-661,713 individuals in all. During the spring of 1916 another imported parasite of the gipsy-moth eggs, known as Anastatus bifasciatus, was colonized in 14 towns in Maine, 31 towns in New Hampshire, and 71 towns in Massachusetts, a total number of 12,286

Re

colonies being liberated, containing 12,286,000 individuals. coveries from colonies previously planted in the field have been_very satisfactory, indicating that both of these egg parasites are doing good work.

Apanteles lacteicolor, a parasite which attacks small caterpillars of the gipsy and brown-tail moths, has been recovered in greater numbers than during the previous years. Meteorus versicolor and another imported Apanteles, A. melanoscelis, have increased satisfactorily in most of the colonies where they were liberated and have spread over a large area from the original colony site. Specimens have been secured this year so that several new colonies could be liberated.

The imported tachinid fly Compsilura concinnata has been recovered in satisfactory numbers this year, and as it attacks many species of native caterpillars it is a very beneficial insect. Another imported tachinid, Zygobothria nidicola, has been found more abundantly than before. The Calosoma beetle has continued its good work although apparently not so numerous in certain localities as it was last year.

DECIDUOUS-FRUIT INSECT INVESTIGATIONS.

Investigations of insects affecting deciduous fruits have been carried on under the direction of Dr. A. L. Quaintance, as in former years.

APPLE INSECTS.-The studies of the codling moth in progress in Colorado in cooperation with the Colorado Agricultural Experiment Station have yielded much valuable information and are being conducted on a larger scale. Laboratory life-history studies have shown that there are in the Grand Valley two broods of larvæ and a partial third brood each year. An investigation has been carried on as to the distance the moths can fly, day and night records of egg laying have been made, the development of the larvæ on the fruit and shoots of the apple has been studied, and a band trap has been devised for use around the trunk and branches of the apple trees which permits the larvæ to enter to pupate but prevents the exit of moths. This trap has been put to a thorough test and has been found to be of great value in codling-moth control. It will doubtless be adopted by orchardists, since it does away with the need of frequent examination of bands for the destruction of larvæ. Orchard spraying and dusting experiments on a large scale are under way, the plats being so arranged that the results should indicate the most effective times and the minimum number of applications of poison for the control of the codling moth under arid conditions.

The investigation of apple-tree borers has been continued and extended. A detailed account of the roundheaded apple-tree borer is in course of preparation. The period during which this insect, in its larval stage, bores into trees has been found to vary from one to at least four years. It has also been found that the common service tree is very largely responsible for the distribution of this borer in the eastern part of the United States. The proximity of the service trees and a few other trees in the woods to young orchards results in a prompt infestation by this insect. Since the adult females mi

grate very little, the insects may be reduced greatly by the destruction of their favorite food plant, the service tree. Various paints and washes have been tested, and several of them have been found to be effective against borers.

Evidence has been gained which indicates that what is called "stigmonose injury" to apples is connected with the punctures of the fruit by aphids, particularly the rosy aphis. Spraying experiments in orchards for the control of the rosy aphis resulted in a considerable diminution of the stigmonose injury.

Important biological studies of several species of apple aphids have been carried on. Further experiments in the use of poisonous gases against the woolly apple aphis in orchards have been made. Carbon bisulphid may be applied to the roots by injection or in water poured around the roots. Many tests have been made to determine the dosage which will be effective against the insect and safe to the trees. An essential part of this investigation has been the determination of the effect of soil temperature and soil moisture on the diffusion of the gas, as well as the behavior of the gas in various types of soil, as in clay, shale, or sandy soil.

GRAPE INSECTS.-The biological studies of the grape Phylloxera in California have been concluded, and manuscript is in course of preparation for publication. Renovation experiments in vineyards have been continued, and show that by the use of deep plowing, fertilizers, and, when possible, irrigation, much benefit may be derived. In cooperation with the Bureau of Soils, investigation of the relation of Phylloxera injury to different types of vineyard soils was continued. This information will be valuable to prospective planters. Field experiments in the control of the grape-berry moth in the Lake Erie Valley have been continued, and the use of arsenical sprays, hand-picking of the infested fruit, and the covering of the fallen infested foliage in vineyards by fall plowing have been tested. Best results in control were found to follow applications of arsenate of lead at the rate of 3 pounds of the paste to 50 gallons of water, applied immediately after falling of the grape blossoms and about two weeks later. Both of the other methods mentioned, however, are valuable adjuncts to the more effective spraying work. Some work upon this insect was done in cooperation with the Ohio State Agricultural Experiment Station at Sandusky, Venice, Put in Bay, and Kelleys Island..

PEACH INSECT INVESTIGATIONS.-Work on the peach-tree borer has been continued, and special attention has been given to experiments in orchards with the use of various poisonous gases to destroy the insects in their burrows around the base of the trees. It seems that from 95 to 100 per cent of the borers can be killed by the application to the roots of from one-eighth to one-fourth ounce of carbon bisulphid in 1 gallon of water. No injury has been noted from the use of this substance at these strengths, although injury results to trees under certain soil conditions from the use of an ounce or more of carbon bisulphid per tree. The relation of soil moisture and of temperature and physical conditions of the soil to the use of this substance is being thoroughly investigated.

NUT INSECT INVESTIGATIONS.-Investigations of pecan insects, with headquarters at Monticello, Fla., have been continued with success;