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