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Grasshopper Forecasting and Suppression in Utah

By Clinton E. Burfitt,  Plant Industry, Utah Department of Agriculture and Food, Salt Lake City, UT.  Clint serves as Survey Entomologist and CAPS Coordinator for UDAF, where he has worked for 10 years.

grasshoppers
grasshoppers
Grasshoppers line an irrigation wheel (top) and oat blades (bottom) in Millard County, summer 2010.


Each year the Utah Department of Agriculture and Food and USDA-Animal Plant Health Inspection Service conduct grasshopper and Mormon cricket surveys in Utah.  The surveys determine nymph populations in spring, adult populations in summer, and sometimes, egg surveys are conducted in the fall.  Information from these surveys is used to forecast the following year’s population densities.  Results of this year’s surveys show that we should see a slight decrease in statewide populations in 2011, although some counties could still have higher than average grasshopper activity.

Grasshopper and Mormon cricket (Anabrus simplex) outbreaks occur throughout the western U.S. states, and they have the potential to significantly impair Utah’s $289 million forage crop industry.  Along with mammals, grasshoppers are the most important grazing herbivores in the world’s temperate grasslands.

Although most species are found in the tropics, there are over 1,000 species of grasshoppers found north of the Panama Canal in North and Central America.  Some species of grasshoppers are also called locusts, which are differentiated by their nomadic behavior and their ability to form large destructive aggregations.

Species of grasshoppers that regularly become pests in Utah are migratory grasshopper (Melanoplus sanguinipes), two-striped grasshopper (M. bivatattus), pasture grasshopper (M. confusus), Packard grasshopper (M. pakardii), clearwinged grasshopper (Camnula pellucida), bigheaded grasshopper (Aulocara elliotti), and valley grasshopper (Oedaleonotus enigma).  A list of species fact sheets can be found at the University of Wyoming’s Grasshoppers of Wyoming and the West website.

Because of the large amount of federally administered lands in Utah (67.1 %), grasshopper suppression is primarily conducted by USDA-APHIS, which is authorized under the Plant Protection Act to protect rangeland from economic infestations of grasshoppers.  The UDAF administers a federally funded cost-share program.  The suppression strategy that is most effective in mitigating outbreaks consists of forming cooperative treatment areas.  This involves coordinating a grasshopper spray program with landowners and representative agencies within an infested area.  On rangeland, insect growth regulators in conjunction with Aerial-Applied Reduced Agent and Area Treatment Strategies lower the risk to native plant and animal species and reduce the cost of control programs.

References:

Otte, D.  1981.  The North American Grasshoppers.  Massachusetts: Harvard University Press.
Haggard, Peter.  2006. Insects of the Pacific North West. Oregon: Timber Press Inc.
National Agricultural Statistics Service.  2010.  “2009 State Agriculture Overview: Utah.” Utah Agricultural Overview.
The Trust for Public Land.  2003. “Funding Profile: Utah.”
L,, Jeffrey, and A. Latchininsky.  2010. “Do more with less, using Reduced Agent and Area  Treatments (RAATs) Aerial-Applied Strategies.” In:  Grasshoppers: Their Biology and Management.