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.
Grasshopper 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.
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!