JUL 3- June 1%7 ~ A « I ? RARY ^T 27 STATE PLANT BOARD United States Department of Agriculture Agricultural Research Administration Bureau of Entomology and Plant Quarantine CONTROLLING THE JAPANESE BEETLE By C. H. Hadley Division of Pruit Insect Investigations The Japanese beetle ( Poplllla jaoonlca Newm. ) feeds on the leaves, and sometimes on the blossoms and fruit, of many kinds of trees, shrubs, and farm crops, and on the roots of grasses and other plants. It is native to Japan, and was accidentally introduced into the United States in New Jersey some time prior to 1916. Since that time the infestation has increased and spread, so that it now occurs in all States east of and including Ohio, West Virginia, Virginia, and North Carolina. However, the infestation is much more general and continuous along the Atlantic seaboard than in the States to the westward. HOW TO RECOGNIZE THE JAPANESE BEETLE The adult Japanese beetle is nearly half an inch long, about one- fourth inch wide, broadly oval, and shining metallic green. The hard outer wings are coppery brown. There are two small tufts of white hairs just behind the wing covers and five patches along each side of the body, which make the Japanese beetle readily distinguishable from other beetles. The newly hatched larva, or grub, is about one-sixteenth inch long, has three pairs of legs, and has the general shape of a blunt-ended crescent. When fully grown it is about an inch long and resembles the white grubs, or grubworms.» SEASONAL HISTORY The Japanese beetle normally requires one year to pass through all stages of its development. In the latitude of Philadelphia the beetles usually begin to emerge from the soil between June 10 and 20, and they are present in considerable numbers by July 5» The feeding season reaches a peak the last of July or the early part of August. The normal life of a beetle is from 30 to U5 days, but a few may be found as late as October. At more southern points beetles are active earlier in the season; farther north they appear later. On warm, sunny days the beetles fly about from one plant to another. They tend to collect in groups and to feed on certain plants, leaving others, apparently equally attractive, untouched. From time to time they burrow into the ground to a depth of 2 to k inches, where they lay eggs. Por this purpose the beetles prefer medium-moist, loamy soil with closely I8H - 2 - cropped grass, such as is found in lawns, pastures, and golf greens and fairways, but some eggs are always placed in less favorable situations, such as flower beds and cultivated ground. Bach female lays from UO to 60 eggs. The eggs hatch about 2 weeks after they are laid, and the young grubs feed on the roots of grasses and other plants. The grub stage continues through the fall and winter and until the latter part of May or early in June of the following year. In the summer and early fall the larvae feed mostly in the upper 3 inches of the soil, but as winter approaches they go down to a depth of 3 to 6 inches, moving nearer to the surface the following spring. FEEDING HABITS AND FOOD PLANTS OF THE BEETLE The beetles feed chiefly on the leaves on the upper and outer parts of plants and trees exposed to "bright sunlight, during the warmer part of the day. On cloudy or cool days there is almost no feeding. The beetles eat the tissue between the veins of the leaves, causing the leaves to become skeletonized. Leaves that have been thus injured soon turn brown and fall, and as a result preferred food plants in heavily infested areas are often entirely stripped of their foliage. When the infestation is very severe, even large fruit and shade trees may be completely defoliated within a few days. The Japanese beetle is known to feed on more than 275 different plants, but most of the injury is confined to comparatively few of the more favored species. The beetle is an important pest on early-ripening fruits, especially apples, peaches, and plums. The beetles often con- gregate in masses on the fruit and eat until only the core, stone, or pit is left. Prematurely ripened or imperfect fruits are preferred, but where the infestation is heavy, nearly all the fruit may be injured. Late varie- ties of fruits usually escape attack. Beetles also cause much injury to field and sweet corn by feeding on the silk as it grows out from the husk before pollination takes place. The destruction of the green, immature silk prevents pollination and sub- sequent development of the kernels. Among field crops other than corn, soybean and red clover are most likely to be severely attacked. Asparagus, rhubarb, and beans are subject to attack, but most of the other common vegetables are rarely injured. FEEDING HABITS OF THE LAEVA The grubs of the Japanese beetle frequently cause severe injury to turf in lawns, golf courses, parks, and pastures. As they burrow through the soil, the grubs cut and feed on the rootlets of grass, causing it to die out in small -oatches or larger areas. Turf killed in this manner can be rolled back easily, disclosing the larvae beneath. Considerable injury is also caused at times by the grubs feeding on the roots of strawberry and corn, bean, tomato, beet, onion, and other vegetables, and ornamentals, such as iris, peony, gladiolus, and snapdragon. - 3 - CONTROLLING THE AIULT BEETLE Sprays containing DDT, lead arsenate, rotenone, and a lime- aluminum sulfate combination have been used successfully for protecting foliage and fruit from beetle attack, although no material has been found entirely satisfactory for protecting flowers highly attractive to the beetle. The DDT spray ifl preferred, as it kills rather than repels the beetles, is cheap, and leaves an inconspicuous residue that usually protects the foliage for several weeks. The lead arsenate spray is also effective for a long period, but it acts chiefly as a repellent and leaves a conspicuous deposit which under some conditions may be objectionable. The other sprays are suggested where the use of DDT or lead arsenate is likely to leave harm- ful residues on fruits and vegetables. Timeline S8 and thoroughness in the application of sprays are ^ery important. As a general rule, especially in localities where the beetles are very numerous, the first spray should be applied when the beetles are first seen, before they become established on the plants. In heavily in- fested localities it is often difficult to prevent injury if the spraying is delayed until beetles appear on the plants. Where the infestation is not dense, the first application may be delayed until the beetles begin to concentrate on the plants to be protected. DDT Sprays and Dusts Fruit and ornamental trees and shrubs may be protected by spraying or dusting them with DDT. The spray is prepared by mixing 2 pounds of a wettable powder containing 50 percent of DDT in 100 gallons of water. For smaller quantities use 3 ounces (l6 tablespoonfuls) of the 50-percent DDT powder in 10 gallons of water or h teaspoonfuls per gallon. If a wettable powder containing a different percentage of DDT is used, the quantities 'should be adjusted accordingly. The DDT may be used alone or in combina- tion with a fungicide, such as wettable sulfur. One application of the spray is usually sufficient to protect the fruit and foliage of many fruit trees. A second application L or 3 weeks later may be required on ornamental trees and shrubs and on grapevines, to protect new growth. When a second application to grapes is necessary, only half the amount used in the first spray should be used. Dusts containing 5 to 10 percent of DDT have been used with some success, but they are less effective than the DDT sprays. DDT should not be used on fruit that is about to ripen; other sprays, discussed later, are preferable. DDT sometimes causes various species of mites to increase in abundance, probably by destroying their natural enemies. Lead Arsenate Spray The foliage of fruit trees of late-ripening varieties and ornamental trees and shrubs may be protected by spraying with lead arsenate. This spray is prepared by mixing lead arsenate and common wheat flour in the following proportions: - 1* - Lead arsenate For 100 gallons . . 6 pounds Wheat flour .... k pounds For 10 gallons For 1 gallon 10 ounces 1 ounce (k 1/2 table spoonfuls) 6 ounces 0.6 ounce (2 tablespoonfuls) Other stickers, such as raw linseed oil or fish oil, may he substituted for the flour at the rate of k fluid ounces to each pound of lead arsenate. The lead arsenate spray for Japanese beetle control is not advised for use on early fruits, ripening in July or August. PRECAUTIONS IN USING LEAD ARSENATE OR DDT.— Lead arsenate is poisonous to man and animals. In handling it one should take care to avoid inhaling the dust. It should be kept in plainly labeled closed containers away from food products, and where children or pets cannot reach it. Since it is possible that the poison may be absorbed into the system through cuts and scratches on the skin, it is advisable to protect the hands. The worker should keep his hands away from his mouth and wash them thoroughly before eating. Children and domestic animals should be kept from playing or feeding on the poisoned turf until it has been watered or rain has fallen. The extensive use of lead arsenate on lawns within the heavily infested area has not caused any known damage to poultry or native birds that feed on earthworms and grubs in the soil. Similar precautions should be observed in handling DDT. Other Sprays The following sprays have been used successfully to protect fruits and vegetables that cannot be treated with DDT or lead arsenate: Lime-Aluminum Sulfate Spray For 10 gallons For 100 gallons For 1 gallon Hydrated lime (for spraying). 2 pounds 20 pounds 1 measuring cup Aluminum sulfate 1/2 pound 3 pounds 2 tablespoonfuls Dissolve the aluminum sulfate in about 1 quart of water (or 2 gal. when preparing 100 gal. of spray) and add it to the partly filled spray tank while the agitator is in motion or with frequent stirring. Then make a thin paste of the lime and wash it through a screen (to remove lumps) into the spray tank before adding the remainder of the water. - 5 - Rotenone-Rosin Emulsion Spray For 10 gallons For 100 gallons For 1 gallon Rotenone-bearing material. . 5 ounces 3 pounds l/2 ounce Ro sin-residue emulsion ... 5 ounces 3 pounds l/2 ounce As the source of rotenone, ground derris, cube, or timbo may be used, provided the material contains not less than h percent of rotenone and not less than 16 percent of total extractives. The rosin emulsion can usually be obtained in the emulsified form from insecticide dealers. To prepare the spray, wash the rosin emulsion into the partly filled spray tank. Make the rotenone material into a thin paste with water and wash it into the tank with the agitator running or with frequent stirring before adding the remainder of the water. Fruits ripening at the height of the beetle season are the most severe- ly attacked and the most difficult to protect. To avoid harmful residues DDT should not be used on the fruit trees later than 2 weeks, and lead arsenate not later than 3 to 4 weeks, before harvest. The lime-aluminum sulfate spray has been used with satisfactory results for the protection of early apples; for peaches, nectarines, and plums the rotenone spray is preferable. It is important that the protective covering on the trees be adequate to overcome the natural attractiveness of the fruit. Fruit ripen- ing after the height of the beetle season is seldom eaten by the Japanese beetle, but insecticides are sometimes necessary to protect the foliage. DDT may be used in such a case if applied no later than 3 or ^ weeks be- fore harvest. Neither DDT nor lead arsenate should be used on raspberry, black- berry, and blueberry bushes until after the fruit has been harvested. Application of the rotenone spray will afford some protection, depending on the beetle population, ripeness of the fruit, and weather conditions. Only a few of the common garden vegetables are seriously injured by the beetles. Most of these few may be protected by spraying or dusting with DDT, When portions of the plant that are soon to be eaten are ex- posed to the spray, as in the case of string beans, DDT should not be used. The nonpoisonous lime- aluminum sulfate spray should be used instead. Vegetables in home gardens can be given some protection by dusting with a good grade of fine hydrated lime. Corn may be protected by applying, to the silk, a dust containing 5 to 10 percent of DDT. However, if the corn fodder is to be fed to live- stock, DDT should not be used; hydrated lime is preferable. Roses are especially susceptible to attack and are difficult to pro- tect. The most practical method is to disbud them during the period of beetle flight, and protect the leaves by spraying with DDT or lead arsenate - 6 - as already discussed. It has been found that plants treated in this manner will thereafter have a profusion of "blooms of excellent quality, and will bloom later than if allowed to flower throughout the summer. Choice rose and other ornamental plants may he protected from beetle attack by enclosing them with a cloth or wire netting on a wooden or metal frame. When roses are protected in this manner, it may be neces- sary to apply a fungicide during July and August to prevent mildew. CONTROLLING GRUBS IN LAWNS AND OTHER TURF AREAS Insecticides It is possible to make an established lawn practically immune to injury by grubs of the Japanese beetle by applying DDT or lead arsenate. These materials can be applied at any season when the ground is not frozen, but the best results are obtained if the application is made in the spring. The treatment of pasture land is not recommended. For treating lawns or other small turf areas, the DDT should be applied to the surface as uniformly as possible, as a 10-percent DDT powder at the rate of 6 pounds per 1,000 square feet. It may be broadcast by hand or with a small fertilizer distributor. Lead arsenate may also be used, at the rate of 10 pounds of lead arsenate powder per 1,000 square feet. The powder may be mixed with several times its volume of moist sand, soil, or other suitable material, and applied in the same manner as DDT. After application of either the DDT or lead arsenate, the lawn should be well watered with a hose to wash the poison into the soil. Larger turf areas, such as estates, parks, golf courses, or ceme- teries, can be treated more economically by means of a large fertilizer distributor. The DDT should be used at the rate of 250 pounds of 10-per- cent dust per acre, the lead arsenate at the rate of U35 pounds per acre. Where spraying equipment is available, a wettable DDT powder may be used, at the rate of 100 pounds of 25-percent, or 50 pounds of 50-percent DDT powder in 1,000 gallons of water per acre, which is equivalent to approxi- mately 23 gallons per 1,000 square feet of turf. Lead arsenate should be used at the rate of 435 pounds suspended in 1,000 gallons of water per acre. MILKY DISEASE Like human beings, the Japanese beetle is subject to disease. The most important one that kills many grubs is known as the milky disease, caused by tiny germs, or bacteria. In a diseased grub the blood, usually clear, assumes a milky color. The milky-disease germs, or spores, live in the soil for long periods, ready to infect and kill successive broods of Japanese beetle grubs as they move about in the soil, feeding on plant roots. Fortunately, the disease is harmless to human beings, warm-blooded animals, and plants. - 7 - Workers in the Department of Agriculture have invented devices and methods by which inoculated grubs are used for the production of spores of the milky-disease organism in the laboratory. The grubs, after being thus infected, are ground and mixed with talc to form a "spore dust mixture, which can be applied to turf and other grass areas to destroy the grubs. The spore dust is available commercially with directions for its use, and may be applied by individuals, or preferably by community groups, to control the grubs in the soil. The disease usually works slowly, and it may be several years before its full effect is evident. If there are nearby sources of Infestation, tho use of the disease in a small area will not keep the beetles from flying in from outside and causing serious damage to trees and shrubs. UNIVERSITY OF FLORIDA 3 1262 09227 9982