integrated pest management

Differential Grasshopper Melanoplus differentialis
Migratory Grasshopper Melanoplus bilituratus
Red-legged Grasshopper Melanoplus fermur-rubrum
Crickets Gryllid spp.
Long-horned Grasshoppers Tettigoniid spp.

The differential grasshopper is the largest economically important species. It is 1-1/2 to 1-3/4 inches long, yellowish, with brown and black markings and distinct chevron-like black markings on the hind legs. The adults of migratory and red-legged grasshoppers are about 1 inch long--reddish-brown above and yellow beneath, with red-tinged hind legs. The nymphs are wingless, but otherwise resemble the adults. The elongated, brown-to-orange eggs (glued together in masses) form a pod in uncultivated soil,usually 1 to 2 inches below the surface. The differential grasshoppers winter as eggs and do not appear as adults until summer.

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Meadow Grasshopper
Figure 1. Meadow Grasshopper

Grasshoppers feed on nearly all cultivated and wild plants. The differential and red-legged grasshoppers prefer luxuriant vegetation, while the migratory grasshoppers prefer sparse vegetation. All three species are found throughout Illinois, but the migratory type is found in greatest numbers in the southern sections.

Life History
Injurious grasshoppers winter as eggs, which hatch from mid-May in southern Illinois to July in northern Illinois. The nymphs shed their skins several times, reaching maturity in 6 to 8 weeks. The adults continue to feed until fall. when they mate and the female lays eggs. During September and October, a single female will lay several egg pods containing from 15 to 120 eggs. The eggs are deposited 1 to 2 inchess belopw the soil surface in field margins, fencerows, ditch banks, roadsides, and sod land. Hot, dry weather favors grasshopper developmenr. In wet, humid weather, diseases (bacteria and fungi) kill of many hoppers.

Grasshoppers are chewing insects that feed from the outer edges of leaves inward. When numerous on corn, they even eat part of the stalk and ears. They attack fresh silks, reducing pollination and often causing the ears to be blank or only partly filled. Even light infestations of 6 or 7 grasshoppers per square yard in a 10-acre hay field will eat as much hay as a cow; 17 hoppers per square yard in a 40-acre hay field will eat a ton of hay a day. All types of field crops, vegetable crops, fruit crops, flowers, and shrubs are subject to attack.

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Grasshopper Feeding Damage to Corn
Figure 2. Grasshopper Feeding Damage to Corn

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Grasshopper Damage to Corn
Figure 3. Grasshopper Damage to Corn

Grasshoppers have many natural enemies. Among the more-important ones are flesh flies, bee flies, blister beetles, ground beetles, spiders, hairworms, rodents, birds, and diseases.

Pests Related To Grasshoppers
Crickets differ from grasshoppers by having antennae about as long as their bodies. They are dark-colored, except for the tree crickets which are green. The females have a long, straight egg-laying tube. Some species are winged, while others are wingless. Crickets make a characteristic chirping sound, usually in unison. They feed mostly at night on a variety of materials. Field crickets can be found nearly everywhere in pastures and gardens, where they hide under stones, leaves, and other objects on the ground or burrow into the soil. Most crickets feed on plants, but some types are predaceous. Tree crickets live among herbaceous and woody plants, and the females (with their long, sturdy egg-laying tube) sometimes split open small branches and cause serious damage. Other types include the soil-inhabiting mole crickets, the ant-loving crickets and the bush crickets. Control of crickets is rarely necessary under Illinois conditions

Long-horned Grasshoppers
These long-legged, jumping insects also differ from grasshoppers by having long antennae. The females have a long, curved, nearly sword-shaped, egg-laying tube that distinguishes them from crickets. All katydids are green; crickets are dark brown to black, except for the tree crickets. Both winged and wingless species occur. Katydids so closely resemble grasshoppers they are often called long-horned grasshoppers. They are found almost everywhere, but seldom in large numbers. They feed at night on plants and small animals. Their characteristic chirping sound is frequently heard. Control is rarely if ever necessary.

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Red-legged Grasshopper
Figure 4. Red-legged Grasshopper

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Grasshopper Egg Pod
Figure 5. Grasshopper Egg Pod

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Differential Grasshopper
Figure 6. Differential Grasshopper

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