But in some areas, the plague of hoppers virtually wiped out everything that sprouted.
"In western Montana, especially in Sanders County, it was as bad as I have seen in my 15 years," said Gary Adams, state plant health director of the U.S. Department of Agriculture's Animal and Plant Health Inspection Service in Helena.
Adams' agency recently published the 2004 Rangeland Grasshopper Hazard Map for the entire western United States. It is based on data collected during the early summer of 2003.
Four colors denote various grasshopper hazard magnitudes - blue, green, orange and red. Red denotes the most extreme infestation of 15 or more grasshoppers per square yard. Scientists have found that a population density of 20 adult clear-winged grasshoppers per square yard will consume the entire available yield of forage grasses on intermountain rangelands.
"There were places last summer in Sanders County where there were over 100 grasshoppers per (square) yard on the mating beds," Adams said.
Populations of the clear-winged grasshopper exhibit cyclic extremes of abundance and distribution, according to USDA scientists. The species can remain virtually unseen for five to 10 years, then increase gradually over three to four years and reach peaks the following two to three years. During the period of increase, a population may spread from a few acres of rangeland to more than 2,000 square miles.
The cause of outbreaks appears to be a combination of factors - favorable weather, nutritious host plants, and reduced rates of predation, parasitism and disease.
The best control appears to be a cold winter. Low soil temperatures in winter may cause up to 100 percent mortality of eggs, the USDA says.
The federal government doesn't have many programs to help farmers and ranchers who experience significant damage from hopper infestations.
The only one of note is the APHIS cost-share program, which is limited to relatively large landholdings - 2,000 acres or more - and helps pay for the cost of pesticides.
Monday's meeting at Lonepine will focus on the environmental factors that affect grasshopper populations, available control methods, how to assess the need for control, and how to select appropriate, cost-effective methods to control the grasshoppers early on, before they spread.
The meeting is sponsored by the Confederated Salish and Kootenai Tribes' Lands Department, the Western Montana Stockgrowers Association and the Montana State University extension agents of Lake and Sanders counties.
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