It is possible that a successful soil treatment with DDT or one of the other new insecticides eventually will be developed for control of white grubs as pests of cereal and forage crops.

CULTURAL METHODS of control often are of limited value. Also, they must be applied before or at the time a crop is sown and before it becomes infested. Some farmers therefore tend not to use them; they do not like to make changes in their established routine to forestall insect infestations that may or may not attack their crops at some future time. What they want is some control measure that can be applied immediately if or when their crops are actually being injured. With the advent of new and more efficient insecticidal chemicals and the currently higher yields and value of some cereal and forage crops it has been increasingly possible to meet this need through the use of insecticides.

BECAUSE ALL insecticides are more or less poisonous to man and other warm-blooded animals, as well as to insects, the usefulness of most of them on cereal and forage crops is limited. When these crops are treated according to recommendations with any of the insecticides mentioned in the following discussions, the amount of insecticide residue that remains on them at harvesttime is too small to be appreciably toxic to animals fed on hay, forage, or silage made from the crops. On the other hand, these feeds may retain very small amounts of the insecticide and when fed to farm animals may cause the deposition of very small quantities of it in their body tissues, milk, or eggs. What effects, if any, the consumption by man of extremely small quantities of these insecticides in meat, milk, eggs, and other foods may have on human health is still in doubt. Therefore, except as otherwise indicated in this article, forage, hay, or silage from crops that have been treated with any of these insecticides should not be fed to dairy animals or poultry, or to meat animals being finished for slaughter.

DDT and toxaphene in sprays or dusts are two of the best insecticides yet tried for the control of the true armyworm, fall armyworm, and army cutworm, but some investigators have reported poor results. Also, the advisability of using them on grain and feed crops is still questionable because of the residues of insecticide that may remain on them at harvesttime. These insects are really cutworms that appear in great numbers some years when weather conditions are favorable to extensive outbreaks. The true armyworm and army cutworm are partial to small grains, grasses, and corn, but the fall armyworm also attacks peanuts and other legumes. Excellent control has been obtained by application of a spray made from factory-prepared concentrated solutions of toxaphene or DDT which are emulsifiable with water. Toxaphene has been successfully applied by airplane at the rate of 1.5 to 2 pounds per acre in 2 gallons of spray. A spray containing 1.5 pounds of DDT in 5 gallons of spray per acre has also given satisfactory control when applied by airplane or with ground equipment. Dusts containing 20 percent of toxaphene or 10 percent of DDT, applied at the rate of 20 pounds per acre, have also given good control under some conditions.

The broadcasting of poison bran bait as commonly applied for cutworms and grasshoppers is another of the good methods of control for armyworms. It has been used for many years. It is less likely than dusts or sprays to leave a residue of insecticide on the crop.

According to Connecticut Agricultural Experiment Station workers, "Thirty pounds of 10 percent toxaphene dust or 10 percent chlordane dust per acre applied to the surface of the soil at least a week before planting gave excellent control of cutworms on tobacco. Toxaphene emulsion, at the same rate of active ingredient per acre was equally effective."

Similar results on vegetable ground with 5 percent DDT or 5 percent chlordane dust at 30 to 40 pounds per acre have been reported by the Minnesota Agricultural Experiment Station. These treatments would appear promising for cutworm control in young corn. In fact, the application of 1 to 2 pounds of toxaphene per acre in two or more gallons of spray with conventional weed sprayers, as recommended by the Iowa Station, has successfully controlled cutworms on hundreds of acres of young corn in Iowa.

CHINCH BUGS are little black sucking insects that attack corn, sorghum, small grains, and grasses grown for forage or lawns in the Central and Eastern States. They are about one-eighth inch long when full-grown, with white wings folded on their backs to form a sort of X. When newly hatched, they are smaller than a pinhead, red, and wingless, but their wings develop and they lose their red color as they mature. They often become extremely abundant in small grains. When these ripen the young bugs migrate in enormous numbers on foot to adjacent fields of young corn, sorghum, and other crops belonging to the grass family. Barriers of one kind or another are widely used to prevent these migrations.

Chinch bug barriers are made in several ways, but the best of them include a narrow band of a repellent or insecticidal chemical on the surface of the soil. For many years repellents such as coal-tar creosote have been used for this purpose, either directly on the ground or on a fence about 2 inches high made of stiff, heavy paper. More recently insecticidal dusts containing 4 percent of dinitro-o-cresol, 10 percent of DDT, or1 percent of benzene hexachloride, applied in a narrow band on smooth, hard-packed soil or in a truck-wheel track, at the rate of 1 to 2 pounds per rod, have been found very satisfactory. The dust line should be patrolled every day to remove leaves or other debris that may have been blown onto it, and to repair any breaks made in it by wind, water, or soil cracks. Lines that have been destroyed by heavy rain should be completely renewed.

Although rather expensive, several of the new insecticides have been recommended as dusts or sprays for application to valuable small plantings of corn and other grains being grown for seed, or to limited areas of corn that have been invaded by chinch bugs from adjacent small-grain fields. Being sucking insects that do not eat plant tissues, chinch bugs cannot be killed by merely spraying or dusting the plants, but must be actually hit with the insecticide. Satisfactory control of the adults on corn has been obtained with toxaphene applied in a spray or dust at the rate of 1 1/2 pounds per acre. One of the best dusts yet found consists of 4 percent by weight of sabadilla powder in pyrophyllite, used at the rate of 50 pounds or more per acre.

Good protection of lawns against chinch bugs has been obtained with a dust containing 5 percent of chlordane by weight applied at the rate of 5 pounds per 1,000 square feet. For more convenient and uniform application this quantity of the dust may be mixed with 2 or 3 pounds of sand or 10 pounds of fine-grained fertilizer and spread with a fertilizer or lime spreader. If no device for settling the dust is attached to the spreader, a broom or the back of a rake may be used. The treatment should not be applied when the grass is wet. Mowing the lawn just before or just after treatment is helpful in perfecting coverage and settling the dust.

THE GREENBUG is a little green plant-louse that frequently does extensive damage to small grains in the spring and early summer in the Central and Southeastern States. No satisfactory control measure for it was known before 1949. Experiments and large-scale use in 1949 and 1950 showed that excellent control can be obtained with parathion at temperatures above 45 F., and with tetraethyl pyrophosphate at temperatures above 70 . These insecticides were used with good effect in 1949 on some 60,000 acres of badly infested small grains in the North Central States and in 1950 on upwards of 650,000 acres in the South Central States. The best results were had with oil or water sprays made from factory-made emulsifiable solutions containing 15 to 25 percent of parathion and applied by airplane or power ground equipment at the rate of 3 to 4 ounces of parathion in 2 to 5 gallons of spray per acre. Tetraethyl pyrophosphate was used at the rate of 4 to 5 ounces per acre in the same gallonages of spray. Both of these insecticides are very toxic to man and contact of any kind with them must be avoided. They should not be applied with hand equipment. They disappear from the plants quite rapidly. However, treated small grains should not be pastured or cut for hay or grain during the first 2 weeks after treatment with parathion or for 3 days after treatment with tetraethyl pyrophosphate.

FOR WHITE-FRINGED BEETLES excellent insecticidal control methods have been worked out. Adult beetles that are injuring ornamental shrubs and flowers may be killed with cryolite or DDT applied as a dust or spray. An undiluted full-strength cryolite dust or a 3 to 5 percent DDT dust is applied at 7 to 10-day intervals. As a spray, cryolite is used at the rate of 1.5 ounces to 1 gallon of water. For a DDT spray, 1 ounce of 50 percent DDT wettable powder, or 2 ounces of 25 percent DDT wettable powder, are mixed with 3 gallons of water, and applied at 10 to 15-day intervals.

Field infestations of white-fringed beetle larvae can be controlled by treating the soil with DDT. One application of 10 pounds of DDT per acre gives good control for several years. The DDT is applied evenly over the soil surface in a dust or spray and mixed thoroughly into the upper 3 or 4 inches of soil with a disk harrow. A good method of applying the DDT is to mix 20 pounds of 50 percent DDT dust thoroughly with 500 pounds of pulverized dry sandy soil or sand enough for treating 1 acre and spread the mixture by hand or with a rotary or spreader-type fertilizer distributor. Even distribution can be obtained by spreading half of the mixture in one direction and the other half at right angles to the first. For garden plots, 1 ounce of 50 percent DDT mixed with a suitable quantity of dry sand is enough for 140 square feet.

For protection of row crops such as corn, cotton, soybeans, and peanuts, DDT is applied in the drill rows at planting time in the spring. The DDT is mixed with soil or sand as previously described and applied by hand or with a fertilizer distributor (at the same depth as the seed is to be planted) at the rate of 2.5 to 5 pounds of DDT per acre.

IN EXPERIMENTAL TRIALS other new chemicals are showing promise as soil insecticides for control of the white-fringed beetle.

Growers of sweet corn in the home garden or for the market usually have trouble with the corn earworm, especially in the warm climate of the Southern and Pacific States, where this insect is a limiting factor in sweet-corn production. A good method of control is to inject a few drops of refined white mineral oil, preferably containing 0.2 percent of pyrethrins, into the base of the silk mass at the tip of the ear with an oil can or medicine dropper about 4 days after the silk first appears, at which time the oil will not interfere with pollination.