LINCOLN, Neb. -- Grasshopper numbers are increasing in parts of Nebraska and are becoming easier to find in grassy borders of crop fields. Now is the time to check for grasshoppers before they become too big to easily control, University of Nebraska-Lincoln entomologists say.



Conditions have been ideal in many areas for young grasshoppers to survive. That makes the best approach to control them now while they are small, relatively easy to control and concentrated in their hatching beds before spreading through crops, said Bob Wright, fields crop specialist in the university's Institute of Agriculture and Natural Resources.



"During grasshoppers' early stages after hatching, they have a very high mortality rate if conditions are cool and wet," Wright said. "However, conditions have been ideal -- hot and dry -- for these young hoppers to survive very well. As a result, we are apt to be dealing with these insects for a good deal of the summer."



The best approach is to control grasshoppers now, because control measures against larger, adult grasshoppers are less effective, said Gary Hein, entomologist at UNL's Panhandle Research and Extension Center at Scottsbluff.



"Because grasshoppers move into cropland from untilled hatching beds around field borders and in grasslands, grasshopper surveys should be conducted in these adjacent untilled areas early in the season," Hein said. "Growers need to watch closely early. If they don't, they could get into a crisis situation."



To estimate grasshopper densities warranting control, count the number of grasshoppers by using a square-foot method, Wright said.



Randomly select an area and visualize a square-foot area. Walk toward that spot and count the number of grasshoppers seen in or jumping out of this area. Repeat this procedure 18 times and divide the total number of grasshoppers by two. This will give the number of grasshoppers per square yard.



Counting sites should be done at random and vary in vegetation. Also, sample both north and south facing slopes.
To sample for grasshoppers within fields where grasshopper density will be lower, use the same method except visualize and count the grasshoppers in a square yard.



Treatment most likely is necessary when there are moderate infestations eight to 14 grasshoppers per square yard within fields and 20 to 40 grasshoppers per square yard in field borders. A light infestation of three-to-seven grasshoppers per square yard in fields and 11-to-20 in field borders may mean treatment is necessary, depending on the size, species and crop. If there are abundant infestations of 15 or more in fields, or 41 or more in field borders, treatment is necessary.



Several insecticides are labeled and effective for grasshopper control on various crops.



For more information about spraying for grasshoppers, consult UNL Extension NebGuide NF32, "A Guide to Grasshopper Control in Cropland," available online as a PDF, or from a local extension office.



A current list of pesticide registrations for various crops also can be found on the UNL Department of Entomology Web site. More information about spraying and grasshopper management is available in Crop Watch, Extension's crop production newsletter.



SOURCE: University of Nebraska-Lincoln news release.