The Japanese Beede DDT Is the Only One of the Newer In- Secticides Whose Use Has Led to Such De- Velopments

The reader should not conclude that increases in importance of previously minor pests following the use of DDT have been confined to apples or that The Japanese Beede DDT is the only one of the newer insecticides whose use has led to such de- velopments. For example, the use of Charles H. Hadley DDT has been associated with in- Walter E. Fleming, creases of mites on peaches, grapes, pe- cans, shade trees, and cotton; mealy- bugs on grapes; aphids on cotton; the Harry B. Weiss, who since became red-banded leaf roller on peaches and director of the New Jersey Division of grapes; and cottony-cushion scale on Plant Industry, found a few shiny, me- citrus. On the other hand, the use of tallic green beetles in a nursery near materials such as methoxychlor has Riverton, N. J., in 1916. He did not been followed by more mites on apples recognize them at first, nor did anyone and peaches and aphids on cotton. The else, but they were finally identified as use of parathion has been followed by Japanese beetles, Popillia japónica. increases of the soft scale on citrus. That was the first record of their occur- But all in all DDT on apple trees has rence in the United States. Entomolog- been more to blame than the others for ical literature contained little informa- outbreaks of pests that used to be of tion about them other than that they little importance. Despite the problems were common on the main islands of its use has created, DDT has been a Japan and were not considered a seri- great benefit to apple growers ; advan- ous pest. We knew httle about their tages resulting from its use far out- habits in Japan and nothing to indicate weigh its disadvantages. whether they would become serious in the United States. We did know that HOWARD BAKER is assistant division related beetles had caused considerable leader of the division.of fruit insect in- trouble in the Old World and in the vestigations. Bureau of Entomology other Pacific islands that they had and Plant Quarantine. He was gradu- invaded. ated from the University of Massachu- Apparently the beetle had come to setts in ig2S and joined the Depart- the United States with plants before ment immediately thereafter. After restrictions w^ere established by the various field assignments having to do Plant Pest Act of 1912. with apple and pecan insects in the The adult Japanese beetle is plump, East, Middle West, and South, he was shiny brown and green with 12 white transferred to Washington in 1944. spots, and about one-half inch long. It is seen only in the summer and may feed on 275 kinds of plants. Its white grub stage is in the ground, where it feeds on the roots of plants. The beetle does damage estimated at 10 million dollars a year to farm and orchard crops, residential and public ornamental plantings, lawns, and golf courses. Men in the Department of Agricul- ture began an investigation in 1917 to get information about its development and habits in its new home. By the end of that year it was obvious that the Japanese beetle. beetle had found ideal conditions for 567 568 Yearbook of Agriculture 1952 its rapid multiplication and was capa- most of the East is normally about 12 ble of causing great losses to many eco- inches. When it is below 8 inches there nomic crops and plants. In 1918 the is such a high mortality of eggs and Department and New Jersey authori- small grubs that beetles are less abun- ties undertook to exterminate it, but dant the following year. A comparison the infestation was so well established of the climates in Japan and the that it could not be eradicated by the United States indicates that the beetle control measures then known and with probably will be able to develop in the funds available. most of the States east of western Scientists then began work to find Kansas. In some States farther west, measures to reduce dijimage and pre- summer rainfall is probably too low for vent its spread. They s^t out to get full survival, except in irrigated lands knowledge of the insqct's life history where adequate soil moisture is main- and habits in its new surroundings ; de- tained. In areas where crops are grown velop measures whereby farmers, home under irrigation, no beetles would de- owners, and others could prevent ma- velop in nearby unwatered areas. In terial damage to crops and plants by northern New England and some other the insect in any of its stages ; develop cold parts of the country, summer tem- practical and economical methods for peratures may be too low for the beetle insuring freedom from infestation of to become established. In most of the commercially grown nursery stock and area now infested by the beetle, few agricultural products so as to prevent die during the winter because a snow spread of the insect throughout the cover usually prevents soil tempera- United States by the movement of those tures from falling to the point where products; and to hasten natural con- hibernating grubs would be killed. If trol of the insect by the introduction the insect should be introduced into and dissemination of its insect enemies certain parts of the northern interior from the Orient and by the practical of this country, where the snowfall is utilization of microscopic organisms normally lighter, the beetle grubs might such as bacteria, fungi, and others be destroyed. found to attack the beetle in any stage of its growth. PROTECTION of fruit and foliage from Detailed information was obtained attack by the adult Japanese beetle in- on the seasonal cycle, behavior, and volves killing the beetles that are on reactions of the Japanese beetle to the plants and keeping the beetles that climatic conditions in both the older fly to the plants from establishing them- area of infestation and in the more selves there. The Japanese beetle at- recently infested northern, western, tacks .orchard crops, small fruits, field and southern areas. This information crops, shade trees, and ornamental was used as a basis for the develop- plants. It is a strong flier, so that during ment of methods of dealing with the the summer there may be continuous insect. invasions of the plantings from the sur- Each year a natural outward move- rounding infested territory. Under con- ment of the beetles from the margins ditions of heavy infestation without the of the area of general distribution protection of sprays, the plants may occurs. Federal and State entomologi- lose all of their leaves and crop. cal workers make surveys each season In the search for insecticides to con- to determine the relative abundance of trol the beetle, many hundreds of ma- the beetle in different parts of the area terials and formulations have been of general distribution. tested, but only a few have given The amount of summer rainfall is promising results. Preliminary tests the main climatic influence on year-to- with untried materials are made in the year changes in the numbers of beetles. laboratory. The few promising ma- Rainfall in June, July, and August in terials found in this manner are tried The Japanese Beetle 569 on a small scale in the field and com- peated applications at relatively short pared with one of the best sprays intervals. DDT in the form of a wctta- recommended for the protection of ble powder or an emulsion, mixed with plants. If favorable results are obtained water at the rate of i pound of DDT in the small tests, the material is used to 100 gallons and applied by a hy- in different localities in commercial draulic sprayer, will kill beetles on orchards, vineyards, and cornfields and early-ripening apples, early-ripening is also applied to shade trees and peaches, cherries, nectarines, plums, ornamental shrubs. and grapes and prevent the reestab- Before 1943 ^^ material had been lishment of the insects on the plants. developed that destroyed the beetles on One application is usually enough to the plants and then remained effective protect the plants until the crop is for several weeks. Sprays containing harvested. After harvest a second ap- soap, or soap arid pyrethrum, kill many plication may be necessary to protect of the beetles that are thoroughly new growth. A single application wetted during the application, but the usually protects the foliage of fruit plants soon become reinfested. Re- ripening in the late summer or early peated applications of the sprays neces- fall. One or two applications have given sary to control the beetles have injured protection to shade trees and orna- the plants. mental shrubs throughout the summer. Whitewashing by several applica- On small plantings of corn, the injury tions of a lime-aluminum sulfate spray to the developing ears can be prevented before beetles become established on by applying the spray or by dusting the plants produces a nonpoisonous with a lo-percent dust when 25 per- coating that repels beetles in lightly or cent of the ears are in silk and repeat- moderately infested areas. It is inade- ing the operation 3 days later. quate when the beetles are abundant. Concentrated sprays of DDT ap- The residue from it is objectionable on plied by airplane or mist blower are ornamentals and is hard to remove effective in controlling the beetle in from fruit at harvest. large acreages of corn and in large-scale Lead arsenate at the rate of 6 pounds spraying of shade trees and ornamen- to 100 gallons of water kills few beetles, tals but have not given satisfactory con- but the deposit repels beetles that come trol in orchards.

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