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Grasshopper infestations high

by Wyoming Livestock Roundup

Cheyenne — Heavy grasshopper populations are being reported in much of Wyoming and one official expects the trend to continue into 2010.
    Maybe it’s only “rural legend” that a colder, wetter spring reduces populations, as that certainly wasn’t the case this year. “A wet spring is one hope, and a thought,” says Bruce Shambaugh with USDA’s Animal and Plant Health Inspection Service Plant Protection and Quarantine (APHIS-PPQ) office in Cheyenne. “But, it never has much affect on a wide scale.” At times the cooler, wetter weather can encourage growth of a fungus that hinders population. This year, however, he says the weather pattern only served to delay what is proving to be a large hatch.
    “I just hope there’s enough grass for the cows and the grasshoppers,” says Gillette rancher Glenn Barlow.
    Fremont County Weed and Pest Supervisor Lars Baker says during early June surveys, timed with the normal hatch, his agency discovered very few grasshoppers. The one exception was the county’s Hidden Valley area.
    “About the third week of June they came out,” says Baker. “Everywhere we stopped we had hoppers.”
    Shambaugh says populations are surpassing what his agency had predicted based on last year’s adult surveys. While several areas had been identified as potential problems, he says the problem wasn’t predicted to be as widespread as it’s proving to be. While infestations aren’t statewide in nature, reports have been received from most eastern Wyoming counties as well as from the Big Horn Basin and Fremont County.
    This year’s hatch, says Shambaugh, was harder to detect amidst the more abundant forage. Now that the grasshoppers have become adults he says they’re easier to spot and their density more noticeable. While Shambaugh’s agency doesn’t specifically address grasshoppers affecting cropland, he says they have received reports of alfalfa, dry bean, wheat, barley and irrigated pasture damage. Similar reports have been made to USDA Agricultural Statistics Service, which mentioned grasshopper damage to crops in its past two issues of the weekly Wyoming crop update.
    It’s too late to effectively control the pests using the preferred and most economical method on rangelands, an insect growth regulator called Dimilin. Some control efforts are, however, being carried out to reduce damage to this year’s crops.
    Baker says some Fremont County crop producers have treated for the pests, but at a cost of $20 to $30 an acre, it’s a tough decision economically speaking. He says the damage has been the most significant in the Hidden Valley area.
    “They are on the rise and I would not expect it to get any better next year,” says Shambaugh. During the coming winter he says his agency is looking to partner with local weed and pest districts and the University of Wyoming to host educational workshops to help producers best prepare for the 2010 season.
    Baker says Dimilin can be utilized in a more economical manner by spraying strips and allowing the migratory nature of the hoppers to bring them to the treatment area. If APHIS chooses to carry out treatment on federal land Baker’s agency will consider partnering, but he says it’s too soon to say if cost share dollars will be available next year.
    Shambaugh says the ideal time to treat grasshoppers is early June, or as soon as they begin hatching. Dimilin, he explains, is a liquid that has a 30-day residual on the foliage where it’s consumed by the grasshoppers. “The main focus is to suppress the populations the current year and that will prevent reproduction and offer multiple year benefits.”
    Cost per acre of Dimilin application is a factor of numerous items including the possibility of local cost share dollars.
    Landowners who would like to report heavy infestations of grasshoppers can do so by calling 866-WYPEST1. Shambaugh can be reached 307-432-7979. Those dealing with the pests in their cropland are encouraged to visit with their local University of Wyoming Extension Agent or Weed and Pest District. Jennifer Womack is managing editor of the Wyoming Livestock Roundup. Send comments on this article to

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