Grasshoppers In Crops
Grasshopper species prefer
habitats with a variety of host plants, including both grasses and
broadleaf weeds. As a result, they prefer cropland settings with nearby
undisturbed areas such as roadside ditches, crop borders, abandoned
cropland, and over-grazed pastures or rangeland. Field crop problems
usually do not arise from neighboring well-managed rangeland or
pasture. Grasshoppers primarily damage wheat, alfalfa, soybeans, and
corn, but during years of high populations, they will feed and
seriously damage almost any crop, tree, shrub, and home garden.
Grasshoppers do not like dense canopies and are most likely to feed on
field edges and along grass waterways.
 The
primary injury caused by grasshoppers is defoliation, as they consume
and clip foliage as they feed. Grasshoppers also cause direct crop
losses by feeding on ripening grain. With favorable, warm dry climatic
conditions, grasshoppers can hatch and mature two to four weeks earlier
than normal. Early hatching (early May) can threaten establishment of
sugarbeet, corn, or other crops planted in early spring. If
grasshoppers mature early, they can move to nearby crops, such as
pretassel corn, entering the whorl and destroying the developing tassel.
Primary damage to alfalfa is defoliation; however, during years of high
infestation, grasshoppers also will feed on stems and crowns. This
feeding can damage the crowns so severely that plants do not recover,
especially when damage occurs just after harvest. Extensive mid and
late season feeding in sugarbeet crowns also can kill plants.
Grasshoppers have a preference for blossoms and fruit of some plants
(e.g. sunflowers), resulting in considerable loss of seed production.
Early seeded winter wheat is more vulnerable to injury than later
plantings because the plants emerge while adult grasshoppers are still
actively feeding. The newly emerged wheat can be so severely damaged by
grasshopper feeding that it will not establish. Increased grasshopper
pressure also may occur after a light fall frost that kills broadleaf
weeds, such as sunflowers, in areas adjacent to winter wheat.
Grasshoppers losing this forage source may move quickly into winter
wheat and cause damage; however, a heavy frost will reduce or eliminate
grasshopper numbers. Spring wheat and other small grains are most
likely to be attacked late in the growing season. Grasshoppers can
seriously damage maturing small grains as they clip the stems, causing
entire heads to fall to the ground.
Life Cycle
There are three stages in the grasshopper life cycle - the egg, nymph,
and adult. The female lays eggs in the soil and surrounds the eggs with
a frothy liquid that hardens to form a protective "pod". The number of
egg pods deposited by a single female ranges from 7 to 30, and the
number of eggs per pod ranges from 8 to 30, depending on the species.
Typically, a female grasshopper will lay about 100 eggs during the
summer and fall. The potential for an outbreak is increased when
females produce more eggs as a result of better food quality and/or an
extended fall to allow more time to lay them.
Egg pods are deposited in the upper few inches of undisturbed soil in
grasslands, pastures, ditches, field borders, etc. Some grasshoppers
prefer to lay their eggs in soil surrounded by grass roots, and other
species select open areas with accumulations of surface debris. Eggs
are well insulated by the pod and can survive extremely cold
temperatures as they overwinter. Most grasshoppers overwinter as eggs,
but a few species spend the winter as nymphs. Most of the latter are
"bandwinged" grasshoppers that make a crackling noise when in flight.
They are seen early in the spring, normally are few in number, and are
of little concern in cropland.
 Hatching
time is strongly influenced by temperature, with earlier hatching
occurring after a warm spring. The twostriped grasshopper is the
earliest hatching grasshopper of concern in cropland with eggs
beginning to hatch from mid to late May. The eggs of the migratory
grasshopper hatch about a week later, with those of the redlegged and
differential grasshoppers hatching about three weeks after the two
striped. The length of the hatching period ranges from two weeks for
the differential to seven weeks for the redlegged grasshopper
Nymphs start feeding immediately after hatching and usually feed on the
same plants as adults. Because of limited fat reserves, nymphs are
vulnerable to adverse weather just after hatching. Extended cool
temperatures (less than 65°F) and rainy weather during this period
can result in severe nymphal mortality due to starvation. Grasshopper
nymphs go through five stages or instars. After each instar, they shed
their cuticle and grow larger, developing to the adult stage in five to
six weeks. In most years, adult grasshoppers are present by late June
and early July. Adult grasshoppers, the only stage with wings, can
readily move out of hatching areas. Hoppers begin egg laying one to
three weeks after reaching the adult stage and may live two to three
months, depending on the late summer and early fall weather. All
developmental stages are influenced by weather.
Most grasshoppers lay their eggs in untilled soil and must move from
these hatching beds to infest a crop. The exception is the migratory
grasshopper. It may deposit eggs throughout a field, particularly
alfalfa. No-till fields also may have increased risk due to potential
egg laying throughout the field.
Border
Treatments
 In most
years, treating either the crop margin or the border area
surrounding the crop is adequate for control. A border treatment of 150
feet beyond the crop edge should be adequate in most situations,
depending on the size of the grasshopper source area, but season long
control may require up to a 1/4 mile border treatment when the
population source is large. Under extreme pressure, control may be
difficult and multiple border treatments may be required. Using
insecticides with the longest residual activity would be most
effective. The residual activity of the treatments will vary with the
chemical and environmental conditions. It is important to monitor the
border areas and crop margins after treatment to make sure grasshoppers
do not re-enter the field.
Barrier treatment with
the A1 Mist Sprayer is the most cost effective
way to eliminate aphids, bean leaf beetles, bean aphids, grasshoppers,
leaf hoppers, ear worm, corn borer, boll weevils, stink bugs, and other
insect pests. A1 Mist Sprayer's high and low volume mist sprayers
create smaller mist size particles in a 0 to 140' air stream that stays
low to the ground for the best control and uniform coverage; Over,
Under and Around Plant Foliage.
Spray your crops directly and spray roadside ditches, waterways,
fencerows, field perimeters and hard to reach areas using 1/10th the
water and less chemical!
A1 Mist Sprayers
Your Insect
Pest Control Specialists!
This information is derived from Nebraska Cooperative Extension
NF02-328 (Revised May 2004) NebFacts
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