April 04, 2003

LINCOLN, Neb. — If drought persists, Nebraskans will be dealing with another bout of grasshoppers this summer, a University of Nebraska entomologist said. NU Cooperative Extension is suggesting a new control plan for rangeland.

Although it's difficult to predict this early in the year, people need to be prepared for potentially large grasshopper populations, said Gary Hein, entomologist at NU's Panhandle Research and Extension Center at Scottsbluff.

"Last year, an unprecedented number of early spring feeding hoppers infested rangeland in Custer and Dawson counties in the Sandhills," the Institute of Agriculture and Natural Resources specialist said, "while the eastern half of the state had continual problems with normal species hatching in late May and early June."

There are two potential problems this summer, Hein said. The first will be the potential for grasshoppers that overwinter as nymphs in central and western Nebraska rangeland. These will need to be evaluated in April and early May because they will develop into adults in May and control will be more difficult.

"Large populations of these grasshopper species are unusual, but the extreme populations seen last spring are a warning to be on the lookout again this year," Hein said.

The second potential grasshopper problem will be grasshoppers that start to hatch in late May and early June in the eastern part of the state. These summer feeding species typically cause problems across the state in rangeland and cropland.

"By mid to late June, all decisions and treatment options should be exercised. Otherwise, we'll have adult grasshoppers which will be bigger and harder to control," Hein said.

Farmers, ranchers and home and acreage owners need to use control methods during grasshoppers' early stages when they are easier to kill and still in more concentrated areas, he said.

"It's better to deal with it up front rather than trying to catch up," Hein said. "If you can treat them early, you can get better control and use less rates of insecticide."

Environmental conditions will play a big factor in determining the severity of the problem. If conditions during egg hatch are wet and cool, grasshopper survival will be low because the young grasshoppers will starve to death. However, if spring and summer prove to be warm and dry, as forecasters predict, "we'll be in for another serious year," Hein said.

This year, Hein and other NU Cooperative Extension personnel are recommending a new rangeland control program called Reduced Area and Agent Treatments.

These treatments involve using insecticides at lower rates and applying them to alternating swaths in rangeland or grassland, an approach that will reduce both the amount of insecticide and the area treated.

"This program can reduce costs by 40 to 70 percent, but will only reduce control by 5 to 15 percent. And that last 10 percent of control is very expensive and not really that important in the long run." Hein said.

Ranchers also can consider protection-spraying barriers around valuable forage production areas.

"If we continue to have dry conditions and grass is growing slowly, grasshoppers will cause additional stress to already drought-stricken rangeland," Hein said. "In addition, we won't be able to spare much forage. Forage supply is very important this year."

The new treatment approach can be used in hatching areas in pastures and grasslands to help keep hoppers away from cropland, he said. Treating crop borders or areas surrounding crops may be the best way to keep hoppers out of cropland later in the summer.

For yards and gardens, grasshopper management can be effective if areas are relatively small. However, protecting a garden from grasshoppers moving out of a large area or adjacent grassland or cropland may be impossible. The best strategy may be planting early maturing vegetables, or those less attractive to grasshoppers, such as tomatoes and squash.

A vegetation boarder, such as tall, unmowed grass around a garden will provide food and shelter for the grasshoppers and delay their movement. A "trap crop" of attractive plants, such as zinnias or green, watered vegetation, also can be effective.

There are numerous effective insecticides available for grasshopper control in rangeland, various crops and yards and gardens. For more information, consult NU Cooperative Extension NebFacts, NF97-329, A Guide to Grasshopper Control on Rangeland; NF02-328, Guide to Grasshopper Control in Cropland; or NF97-327, A Guide to Grasshopper Control in Yards and Gardens, available on the Web. All also are available at a local Cooperative Extension office. For more information on RAAT, contact a local extension office.

4/4/03-SA

Gary L. Hein - Ph.D.
Entomology
Professor
(308) 632-1369

Sandi Alswager Karstens
IANR News and Photography
(402) 472-3030

Department: Entomology