LESSER MIGRATORY GRASSHOPPER

Background showing badly damaged wheat plant. a, Second-stage nymph; b. fourth-stage nymph; c. adult male; d, female laying eggs; e. adult male in flight; f, egg pod in soil. (All about natural size.)

TWO GRASSHOPPERS

The two grasshoppers illustrated are among the most important and injurious species. The control measures recommended are useful against them and other species.

The differential grasshopper attacks crops over most of the United States but is seldom found north of the southern boundaries of Minnesota and North Dakota. It prefers heavy soil and rank-growing vegetation. Females deposit large egg pods, containing 50 to 75 yellow eggs, just below the ground surface in heavy sod along roadsides, fence rows, and field margins. Eggs are sometimes laid throughout alfalfa fields but seldom in grain or cultivated crops. They are laid during the summer and fall and hatch in the spring. There is only one generation each year.

The lesser migratory grasshopper attacks crops and range vegetation throughout the United States. Females deposit egg pods containing about 20 cream-colored eggs just below the ground surface in grain stubble, alfalfa fields, ditch banks, and weedy field margins. In Northern States eggs are laid in the summer and fall and hatch in the spring. In the South there are two or more generations each year. Adults sometimes gather in swarms and fly long distances.

Control: Sprays are more effective than dusts. Less material is needed and they kill over a longer period. Prepared oil solutions, emulsifiable concentrates, wettable powders, and dusts in various strengths are available at local dealers and may be diluted to suit available equipment. The insecticides may be applied with hand sprayers or dusters, power ground equipment, or airplanes. Take great care in diluting insecticides and adjusting equipment to insure application at the acre-dosages recommended.

In tall or dense succulent crops and in range grass use the following per-acre dosages Aldrin sprays, 2 ounces; dusts, 3 ounces. Chlordane sprays, 1/2 to 1 pound; dusts, 3/4 to 1 1/2 pounds. Toxaphene sprays, 1 to 1 1/2 pounds; dusts, 1 1/2 to 2 1/2 pounds.

Use the lower rate of chlordane and toxaphene for young grasshoppers when long-continued killing action is not essential. Use the higher dosages for older grasshoppers or when kills over a longer period are needed. When it is necessary to kill young grasshoppers before hatching is completed, the higher quantities may extend residual action long enough to kill the rest of the hatch and save the cost of a second treatment.

In dry vegetation and short, fall-seeded grain, bait is usually more effective than a spray or dust. Bait is also useful in gardens and on crops where insecticides applied to foliage might create health hazards. Oil concentrates are best for making dry baits. Measure out enough concentrate to obtain the active ingredient in one of the following quantities: Aldrin, 2 ounces; chlordane, one-half pound; or toxaphene, 1 pound; add kerosene to make one-half gallon of solution. Apply as a finely divided spray to 100 pounds of coarse bran.

To prepare a wet bait, use emulsifiable concentrates, employing the same quantity of active ingredient used in making dry bait. Add water to make 10 gallons of diluted emulsion and mix thoroughly with the bran. Distribute 5 pounds of dry bait or 20 pounds of wet bait per acre. Dry bait is best for airplane application but does not scatter well from wet-bait broadcasting machines. It can be stored and used when needed.

Do not feed forage or chaff contaminated with aldrin, chlordane, or toxaphene to dairy animals, to animals being finished for slaughter, or to poultry. If these insecticides are used on fruits or vegetables, do not apply them to the parts of the plants that will be eaten or marketed. If grasshoppers must be controlled on legumes for seed production while in bloom, spray with toxaphene in the early morning or late evening when bees are not active in the field.

Cultivation after harvest discourages egg laying by the lesser migratory grasshopper in fields of grain stubble. Do not drill grain into unworked stubble. Tillage before seeding will destroy many of the eggs.