Prepare now for second hatch of grasshoppers
This year’s first hatch of rangeland grasshoppers resulted in fewer pests than expected in Western Nebraska, but landowners should prepare for a second, potentially stronger wave of grasshoppers now, said a University of Nebraska-Lincoln extension entomology specialist.
“Our first hatch of grasshoppers this year was reduced, we think, because of the weather. The cold and wet weather starved out a lot of the early, young grasshoppers from that first hatch,” said Jeff Bradshaw, UNL extension entomology specialist.
Western Nebraska generally experiences three grasshopper population peaks early in the year. The first population overwinters as adults or well-developed immature grasshoppers while the remaining populations hatch from eggs. The first of these grasshopper populations emerged about a month ago and caused little damage, but experts expect the second, egg-hatching group to be much worse.
“Right now we’re approaching peak hatch of this second group of grasshoppers. There are certain counties, such as Morrill, Scottsbluff, Lincoln and Box Butte, that are facing large numbers of grasshoppers,” Bradshaw said.
The USDA predicted a large grasshopper population in many western states, including Nebraska, because the large adult population at the end of the summer of 2009 probably laid a large amount of eggs.
Landowners should scout their pastures now to determine if they have an economically important grasshopper infestation, which Bradshaw defined as having an average of 25 to 30 immature grasshoppers per square yard. Treatments should be applied now for maximum protection, said UNL extension educator and grasshopper specialist Dave Boxler. Grasshopper control will be reduced if applications are made later.
Bradshaw recommended treating pastures or rangelands using Reduced Area and Agent Treatments, or RAATs. The RAATs system reduces the amount of insecticide applied by 50 percent by alternating treated swaths of 100 to 150 feet in width with 100- to 150- foot wide untreated swaths. Dimilin 2L is the insecticide used with this system, which has residual activity approaching 28 days. Dimilin 2L is labeled for use on soybeans and wheat but not corn and alfalfa. Dimilin 2L also can be used in non-crop border areas.
Grasshoppers have not been spotted in wheat yet, but they have appeared in border areas. Bradshaw recommended treating these border areas to prevent grasshoppers from moving in to the cropland.
Most grasshoppers develop through five immature stages, or instars, before becoming winged adults. Producers must use the RAATs system when fourth instar grasshopper nymphs appear because it will not work on adults, Bradshaw said.
“Producers who grow alfalfa, corn or soybeans and experienced problems with grasshoppers last year should consider applying a treatment along field borders and into pastures which border their fields. This treatment should be applied now if Dimlin 2L is to be used,” Boxler said.
For more information on grasshopper identification, scouting procedures and additional control options, visit online here. Also visit Market Journal, UNL Extension’s television program for agricultural business decisions, and Crop Watch, UNL Extension’s crop production newsletter.