Grasshoppers
Differential grasshopper, Melanoplus differentialis (Thomas)
Redlegged grasshopper, Melanoplus femurrubrum (DeGeer)
Twostriped grasshopper, Melanoplus bivittatus (Say)
Acrididae, ORTHOPTERA


DESCRIPTION (several species)

Adult - Full-grown grasshoppers range in length from 19 to 38 mm. The differential grasshopper is basically brownish-yellow or olive green with contrasting black markings. On the hind femur, these markings resemble chevrons. The redlegged grasshopper has a reddish-brown back, a yellow belly, and bright red hind legs. The twostriped grasshopper is greenish-yellow with contrasting black or brown markings. It has two light color stripes which run from the head to the tips of the wings. Color plate.

Egg - Grasshopper eggs occur in oval, elongate or curved pods made out of soil particles. Often the size of kernels of rice, eggs may be white, yellow green, tan, or various shades of brown.

Nymph - Newly hatched nymphs are white. However, after several hours of exposure to sunlight, they assume the distinctive colors and markings of adults.


BIOLOGY

Distribution - Grasshoppers occur throughout the continental United States. Extensive grasshopper damage, however, is confined primarily to subhumid, semiarid areas of the country from Montana and Minnesota southward into New Mexico and Texas. The differential grasshopper is most injurious in the Great Plains, upper Mississippi Valley, and southern states. The redlegged grasshopper prefers areas of low, moist soil. The twostriped grasshopper is common throughout North America.

Host Plants - The grasshoppers which damage crops are general feeders. They have been known to cause losses in small grains, corn, alfalfa, soybeans, cotton, clover, grasses, and flax. The redlegged grasshopper displays a preference for alfalfa.

Damage - Although approximately 600 species of grasshoppers occur in the United States, the differential, twostriped, and redlegged grasshoppers are among the most troublesome species in forages. The differential and redlegged species are sporadically of economic concern in North Carolina forages, but the problem is not an annual concern. As a group, grasshoppers cause more damage to alfalfa than any other insect in the Midwest. Each year they destroy at least 80 million dollars worth of forage crops in this country. An infestation of 7 or 8 adult grasshoppers per square meter (approximately 1 yd2) consumes as much forage on a 4-hectare (about 10 acres) lot as one cow. Damage is most severe when hot, dry weather slows the growth of the forage crop thereby preventing a rapid recovery. Color plate.

Life History - The grasshopper species covered in this text overwinter as eggs in the soil. Eggs hatch throughout April, May and June as soil temperatures rise and spring rains begin. The first nymph to leave the egg pod makes a tunnel from the pod to the soil surface through which the succeeding nymphs emerge. Nymphs feed and grow for 35 to 50 days, molting five or six times during this period. Development proceeds most rapidly when the weather is warm and not too wet.

Mature grasshoppers mate and continue feeding on crop plants. About 2 weeks later, females begin to deposit clusters of eggs in the soil. During this process, a glue-like secretion cements soil particles around the egg mass, forming a protective "pod." Each pod may contain 25 to 150 eggs, depending on the species of grasshopper. Grasshoppers which deposit masses containing few eggs usually lay more pods to compensate. Ideally each female may produce 300 eggs. Swarms of grasshoppers usually adopt a specific area as their breeding ground and lay all eggs in that vicinity. Most economically important grasshopper species complete only one generation each year. Redlegged grasshoppers, however, have at least two annual generations and often a partial third in Florida.


CONTROL

Although grasshopper populations occur annually in North Carolina forages, infestations are not usually large enough to warrant control. Populations of 5 medium to large grasshoppers or 8 small grasshoppers per 929 cm2 (1 ft2) are necessary before control is advised on pasture crops. Should populations become threatening, chemical recommendations are available in the North Carolina Agricultural Chemicals Manual.