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Description
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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Figure
1. Meadow Grasshopper
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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.
Damage
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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Figure
2. Grasshopper Feeding Damage to Corn
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Figure 3. Grasshopper Damage to Corn
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Control
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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Figure
4. Red-legged Grasshopper
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Figure
5. Grasshopper Egg Pod
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version
Figure 6. Differential Grasshopper
Authors:
Susan T. Ratcliffe (sratclif@uiuc.edu)
Michael E. Gray (m-gray4@uiuc.edu)
Kevin L. Steffey (ksteffey@uiuc.edu)
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