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 in- secticides 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. Sprays containing i .5 to the plants later. Lead arsenate can- pounds of DDT in the form of an emul- not be used in midsummer on peaches sion or a wettable powder in 5 gallons because of injury to the tree or on other of water have been used with no in- fruits that ripen shortly after spraying jury to the plants. Oil solutions con- because of the excess residue at harvest. taining I pound of DDT per gallon A spray of 3 pounds of derris or cube have caused some injury to the foliage to 100 gallons of water kills many of trees, shrubs, and corn. beetles by contact, but the residue Several chlorinated hydrocarbons keeps beetles away for only 7 to 10 and other new insecticides have been days. It can be used safely on all crops tested as substitutes for DDT since and ornamentals, but the period of 1943. The preliminary results of tests protection it affords is short and the in the laboratory and field with some results vary from year to year because of the materials are summarized. A of the variations in the composition of mixture of piperonyl cyclonene, pyre- the natural product. thrins, rotenone, and cube resins causes DDT so far is the most effective ma- temporary paralysis but kills few beetles terial for killing beetles on plants and and gives little protection to plants. protecting fruit and foliage from later Ryania, chlordane, toxaphenc, aldrin, attack. Dusts containing DDT gen- and dieldrin are of little value. Benzene erally are not satisfactory because their hexachloride gives protection to plants poor adhesive qualities require re- for only a few days. The results with 570 Yearbook of Agriculture 1952 parathion and the oxygen analog of was developed at the Japanese Beetle parathion were similar to those ob- Laboratory about 25 years ago. Many tained with benzene hexachloride. grubs in the turf may destroy the grass TIDE and the ethoxy analog of TDE in a short time. Tests have been con- arc slightly inferior to DDT. ducted continuously to develop better Methoxychlor is practically as effec- materials for grub-proofing and to de- tive as DDT in protecting orchard termine how long different treatments crops, corn, shade trees, and ornamen- are effective in different types of soil tals. Because it is definitely less poi- under various conditions. sonous than DDT to man and warm- Several fumigating methods, such as blooded animals, there is an advantage treatment with dilute emulsions con- in using methoxychlor on forage crops, taining carbon disulfide, methyl bro- on fruits that ripen early in the sum- mide, or ethylene dibromide, are effec- mer, and under other conditions where tive, but have to be applied annually. the use of DDT is not desirable. Other materials have been developed that remain effective for a number of POISONING THE SAP of a plant is a years. novel method for protecting it from Lead arsenate at the rate of 435 attack by beetles. In preliminary tests, pounds an acre has been used for grub- octamethyl pyrophosphoramide was proofing turf since 1929. Among the applied in water to soil at rates up to various arsenicals tested, it is the least 200 pounds per acre. The material did detrimental to grasses. Such grub- not injure the plants, and a sufficient proofing is effective for 5 years or more. amount was absorbed by them to re- Lead arsenate, however, has several duce slightly the feeding by the beetles. objectionable features. It is a slow- Although the protection afforded in acting poison. Its effectiveness and last- this preliminary test was not adequate, ing qualities vary greatly in different the method seems to have possibilities. soils because of its reaction with the different soil constituents. It reduces MANY DIFFERENT TYPES OF TRAPS the effectiveness of certain fertilizers. have been devised, and several hun- Finally, it sometimes makes difficult dred kinds of baits have been prepared the establishment of newly seeded grass. and tested. The most effective trap is DDT and chlordane are effective one painted a primary yellow color and and practical. Like lead arsenate, they baited with a mixture of geranio! and kill the grubs while they are feeding eugenol or with a mixture of anethole on roots or burrowing in the soil. They and eugenol. Although the attractant kill the newly hatched grubs faster than draws beetles from the surrounding the older and larger ones. They work area and thereby increases the num- best at high temperatures and have ber in the immediate vicinity, it is es- little or no effect at temperatures below timated that not more than 25 percent 50° F., when the grubs are practically of the beetles are captured. Traps can- inactive. DDT and chlordane are not not be considered a satisfactory meas- affected by the common fertilizers and ure for protecting plants from attack, soil conditioners. Neither seems to in- but they are of considerable value in terfere with the actions of fertilizers on determining the presence of beetles in plants. The common grasses are toler- localities outside of the known infested ant to both materials. areas. Thousands of traps arc used an- DDT applied at the rate of 25 nually by the Department of Agricul- pounds an acre to established turf kills ture in scouting for new infestations. grubs about two times faster than lead arsenate at the rate of 4.35 pounds an TURF in lawns, parks, and golf acre. Equally good results are obtained courses can be protected from damage with DDT applied as a dust or as a by the grubs by grub-proofing, which spray. Either a wettable powder or an The Japanese Beetle emulsion can be used in preparing the pounds that have been tested as grub- spray. When DDT is applied late in proofing materials since 1946, the best the fall or in the spring, it can be ex- results have been obtained with aldrin pected that about one-third of the fully and dieldrin. Either, at the rate of 3 grown grubs in the soil will be killed pounds an acre, kills grubs 1.5 times before changing to beetles in June. as fast as 10 pounds of chlordane and Both treatments, however, will prac- 4 times as fast as 25 pounds of DDT. tically eliminate by mid-September all The common grasses are tolerant to grubs of the next annual brood that them. The tests have not been under hatch during the summer. The number way long enough to determine whether of years that one application of DDT the effects of aldrin or dieldrin last will be effective in grub-proofing turf long enough to justify recommending has not been determined. The oldest them for grub-proofing. experimental treatment, applied in the spring of 1944, has eliminated eight ISOLATED INFESTATIONS of the bee- annual broods. More recent applica- tle in localities remote from the gen- tions at various localities in New erally infested area can be controlled Jersey, Connecticut, Massachusetts, and the normal rapid increase in the and North Carolina have shown no population greatly retarded by treating sign of reduced effectiveness. the soil with DDT at the rate of 25 DDT has largely replaced lead arse- pounds an acre. This has been demon- nate for grub-proofing because it kills strated with such an infestation in grubs faster, is less influenced by soil North Carolina, where about 250 acres conditions, remains efiFective just as were treated in 1945. The number of long, and is less likely to injure grasses. beetles was reduced to a low level and In 1952 it was cheaper than lead it has not increased very much since arsenate. that time. In contrast, the infestation Chlordane at the rate of 10 pounds in a nearby untreated area increased an acre kills grubs twice as fast as DDT rapidly and spread over the country- at the rate of 25 pounds an acre. A side. Either DDT or chlordane may be treatment applied in September, while used for the treatment of isolated the fully grown grubs arc active, will infestations. kill more than 90 percent of them within 3 wTcks. When the treatment is CHEMICAL TREATMENTS for fruits applied in late fall or early spring and vegetables have been developed to while the grubs are inactive, however, permit their shipment to areas where few grubs will be killed until late in the beetle docs not occur. The shipper the spring. The period during which may choose the treatment that is best one application of chlordanc will be suited to his needs and is least likely efl'ective has not been determined. The to cause damage to the commodity. oldest experimental treatments, ap- Carbon disulfide, vaporized at the rate plied in the spring of 1947 in New of 10 pounds to each 1,000 cubic feet Jersey, Connecticut, and Massachu- in a closed chamber, was the first setts, have eliminated five annual m^ethod developed for killing adult broods. Since chlordane kills grubs beetles in packages of blueberries, faster than DDT, it is more effective blackberries, raspberries, and straw- in reducing populations of grubs in the berries. Because of the explosion haz- spring and fall. When a dense infesta- ard, this material has been replaced by tion is discovered during those seasons, ethyl ene oxide or methyl bromide, damage to turf can be stopped faster which are not explosive at the strengths by an application of chlordane than employed and are equally effective for by using DDT. Both materials are now the fumigation of fruits and vegetables. used extensively for grub-proofing. A DDT treatment has now superseded Of numerous other organic com- the fumigating procedures for potatoes 572 Yearbook of Agriculture 1952 and sacked onions because it is cheaper of 25 pounds an acre (or chlordane at and more easily applied under com- the rate of 10 pounds an acre) has re- mercial conditions. Refrigerator cars placed lead arsenate for the treatment are treated by blowing i ounce of lo of nursery stock. percent DDT dust per 2^500 cubic feet When the stock is grown in the field into the loaded cars. Trucks with in uncertified plots, the infestation may tightly enclosed bodies are treated by be destroyed by immersing the roots in applying i ounce of the dust before and water at a temperature of 112°, or by after loading. dipping the roots in dilute emulsions Methods have been developed for of carbon disulfide, ethylene dichlo- the treatment of soil about the roots of ride, or ethylene dibromide-ethylene plants so that the nurseries and green- dichloride, or by fumigating them with houses within the infested area may methyl bromide in a closed chamber. continue to conduct business in other The use of these methods by nursery- parts of the country. All of the imma- men and others for treating fruits, veg- ture stages of the beetle in soil, com- etables, and nursery stock to satisfy the post, and decomposed manure used for requirements of the quarantine be- potting plants arc destroyed by fumi- cause of the Japanese beetle is discussed gating with carbon disulfide or methyl in more detail in the chapter "OfT bromide in a closed chamber, by mix- Limits for Beetles," page 574^ ing flakes of naphthalene throughout The fact that the beetle, although the material, or by heating the mass to common in Japan, w^as not a pest of 130° F. and maintaining it at this tem- much importance, suggested the exist- pci'aturc for 30 minutes. During the ence of insect or other enemies which seasons when only the grubs are pres- kept it under control. A search for ent, the soil may be fumigated with enemies of the beetle in Japan and chloropicrin or with a mixture of ethy- elsewhere was carried on from 1920 lenc dibromide and ethylene dichlo- through 1933. It was found that a ridc. With these treatments, screening relatively large number of insect para- is necessary when beetles are around,, sites and predators attacked the various to prevent reinfestation. Mixing DDT, stages of the Japanese beetle and re- chlordane, or lead arscnatc with the lated species. About 49 species of insect potting medium will destroy the in- parasites and predators were shipped festation present at the time of applica- to the Department's laboratory in New tion and will destroy any infestation Jersey from Japan, Korea, Formosa, which may be introduced during the China, India, Australia, and Hawaii. following 2 years. Some parasites were released immedi- One of the first treatments to be used ately in the beetle-infested area. Others to destroy infestation about the roots of were used for further study or reared to plants before digging in the field was provide additional parasites for subse- the application of a dilute emulsion of quent release. carbon disulfide. Later, emulsions of Five species of imported insect para- methyl bromide or of ethylene dibro- sites have become established in the mide-ethylene dichloride were devel- beetle-infested area. Two of these, the oped and replaced the carbon disulfide. spring Tiphia {Tiphia vernalis) from The treatments have been satisfactory Korea and the summer or fall Tiphia and practical at the smaller nurseries {Tiphia popilliavora) from Japan, are but are generally impractical at the well established and arc one of the im- wholesale establishments. The applica- portant causes of a decline in Japanese tion of lead arsenate at the rate of i ,000 beetle numbers in the older infested pounds to the acre was developed for area. Both parasites are wasps that at- the treatment of the larger fields. The tack the grub of the Japanese beetle. soil is analyzed each year and the lost The wasp lays an egg on the body of insecticide is replaced. DDT at the rate the grub. The maggot that hatches The Japanese Beetle 573 from the çigg feeds on the grub and minor part in the control of the beetle. destroys it. The first colonies of the Early observations indicated that spring Tiphia were released in 1926 the grubs were subject to several dis- in New Jersey ; by 1951 a total of 2,018 eases. About 25 dififerent soil micro- colonies had been released in 14 States organisms can cause some stage of the from New Hampshire to North Caro- Japanese beetle to become diseased. lina and westward to Ohio. State au- Among these are bacteria, fungi, pro- thorities, using wasps collected locally tozoa, nematodes, and viruses. The bac- from the sites of earlier releases made teria causing the milky diseases of the by the Department, released several Japanese beetle grubs were found to hundred additional colonies. The fall be the most important of the organ- Tiphia was first released in 1921 in isms. These are sporeforming bacteria, New Jersey; by 1951, 767 colonies were Bacillus popilliae and B. lentimorbus. released in nine States. The former, the more important, Surveys were made between 1935 causes the type-A milky disease. A more and 1951 to determine the distribution complete discussion of the milky dis- of the spring Tiphia. By the close of ease begins on page 394. the 1951 season the parasite was gen- Another disease found in Japanese erally distributed over an area of some beetle grubs is the blue disease, so- 5,300 square miles in eastern Pennsyl- called because of the bluish tint of vania, Delaware, and southern New infected grubs. Its causal organism is Jersey. It also occurred at many scat- believed to be a virus. The disease tered points in the beetle-infested ter- seems to be very potent and may lend ritory outside of this area. Because the itself to large-scale utilization in much wasp attacks only the grub stage of the the same manner as the milky disease. beetle in the ground, any estimate of Several species of nematodes, tiny the effectiveness of the parasite must be microscopic worms commonly found based upon the actual number of para- in the soil, cause considerable mortality sitized grubs in proportion to the total among the grubs and are an important number of all stages of the beetle found factor in biological control. Their in the ground at the time of the sur- effectiveness depends much more on vey. The surveys disclosed a range of favorable climatic and soil conditions parasitization from 19 to 61 percent, than do the milky diseases, however. with a general average of about 43 per- Several species of fungi attack the cent. The spring Tiphia is the most ef- Japanese beetle. The most important fective of the introduced insect para- is the green muscardine fungus, Metar- sites of the beetle, but the other estab- rihizium anisopliae. It is widespread Hshed parasites are also contributing and under favorable conditions is im- to the reduction of the beetle popula- portant in the biological control of the tion. beetle. The native insect parasites and pred- ators of white grubs occurring in the CHARLES H. HADLEY was an ento- area infested by the Japanese beetle mologist in the division of fruit insect have been studied to find out to what investigations of the Bureau of Ento- extent they attack the beetle. Occa- mology and Plant Quarantine. He was sionally grubs have been found parasi- in charge of Japanese beetle investiga- tized by native Tiphia wasps. A species tions, with headquarters at the Japa- of Ptilodexia, a fly known as a parasite nese Beetle Research Laboratory at of white grubs, was found attacking Moorestown, N, J., until he retired in Japanese beetle grubs to an extent that Í952. suggested that it may ultimately be of WALTER E. FLEMING is also an ento- importance in biological control. With mologist. He succeeded Air. Hadley at this exception native parasites and Moorestown aiid is in charge of the predators appear to play at best only a station. 070184"—52- -3S