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Grasshopper populations inconsistent in 2019, never too early to plan for next year

by Wyoming Livestock Roundup

Published on Jan. 11, 2020

Statewide grasshopper populations were unusually spotty and inconsistent this past year, according to USDA’s Animal and Plant Health Inspection Service (APHIS) Domestic Program Coordinator Kathleen King. 

            Grasshopper survey activities began December 2018 with 14 public meetings held through April 2019.

            “At our public meetings we started talking to people – landowners, stakeholders and the Bureau of Land Management (BLM),” said King. “We also had two grasshopper identification workshops, which really helped those on the ground identify nymphs from adults and males from females, and they were also able to practice density counts.” 

Nymph surveys

            King explained they had boots on the ground conducting nymph surveys early in the year, but they had little luck finding the densities they thought they would find. 

            “We spent six weeks in Fremont County looking and looking. There were a little here and there, but we didn’t find the big hatchout we were looking for in order to go ahead with treatments,” she said. “But it finally came.” 

            “Overall, grasshopper populations were spotty and inconsistent in density and age,” she added. “In most places it seemed as if the hatch was two or three weeks late and it was prolonged. Instead of lasting a few weeks, it lasted five or six.”

Grasshopper treatments 

            King noted APHIS conducted three surveys in the state of Wyoming this year – two in Johnson County and one in Hot Springs County. 

            “Our first treatment was in Johnson County starting June 24 and finishing June 28,” she explained. “Block acres were 48,346. We had three planes in the air and we were able to start at 6 a.m. and spray until the afternoon depending on when the wind shut us down.” 

            “We didn’t have any major issues with our first treatment and everything went as well as expected,” she added. 

            King explained prior to the treatment, counts were as high as 50 grasshoppers per square yard and after the post-treatment survey four weeks later the counts were down to three grasshoppers per square yard. 

            The second treatment also occurred in Johnson County. 

            “We started July 5 and ended July 7. Block acres were 28,722. We had one plane in the air and we did have some trouble with the contractor,” King noted. “Counts before treatment were 30 grasshoppers per square yard and four weeks later, during the post-treatment survey, counts were four grasshoppers per square yard.” 

            She continued, “Our third treatment was in Hot Springs County starting July 10 and running through the 14. Block acres were 54,137 and we had three planes in the air.” 

            King explained because grasshopper treatments usually happen in June, they were afraid this treatment was too late to be efficient. However, the program had good efficacy. 

             “Prior to the treatment, the counts were around 30 grasshoppers per square yard and after the post-treatment survey they were three per square yard,” King said. “All three of these programs were successful as we were able to suppress the grasshopper populations in these areas.” 

Future predictions

            King noted adult grasshopper surveys are used to predict grasshopper populations for the next year, and surveys were conducted in every county last year. 

            “There is a lot of panic about grasshoppers, but we are not near as close to populations we had in 2010,” she said. “There are a few areas of concern across the state, however, including areas in Johnson, Washakie, Sheridan, Campbell, Converse, Natrona, Platte and Hot Springs counties.” 

            “When we look ahead to the future and how to move forward, the minute we decide on a plan, Mother Nature is just going to do something different,” King said. “So for now, the plan is preparation and this includes talking to other Weed and Pest folks, stakeholders and aerial applicators, holding public meetings and getting BLM involved.” 

            King explained the earlier individuals can sit down and have these conversations, the more efficient grasshopper management in the coming year will be. 

            Hannah Bugas is the assistant editor for the Wyoming Livestock Roundup. Send comments on this article to

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