The 2012 Colorado grasshopper hazard map, based on a 2011 survey of adult grasshopper activity, shows that there will be low to moderate grasshopper populations in northeastern Colorado, with the exception of small localized spots with higher risks around Logan, Weld and Yuma counties.

"We are seeing hatching of grasshoppers in the Front Range (of the Rocky Mountains) areas as well as northeastern Colorado," says Assefa Gebre-Amlak, a Colorado State University regional pest management specialist.

Grasshoppers Hatching In Northeastern Colorado

"Weather conditions will determine how much of the damage potential will be realized in those high risk areas. Cool wet conditions after hatch can result in enough mortality in immature grasshoppers to prevent an outbreak.

"If adequate moisture is available, forage regrowth will offset much of the grasshopper damage. Most grasshopper outbreaks occur when drought conditions are prevalent."

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Producers in high risk areas should be monitoring pest populations in rangelands soon after grasshopper hatch, which can last through late June. Early scouting is important, says Gebre-Amlak, because treatments are most effective when grasshoppers are small. The goal of scouting is to get an estimate of grasshoppers per square yard, as well as their stage of development.

The economic threshold for treating grasshoppers on Colorado range is 15-20 nymphs per square yard. This number is equal to  eight to ten adult grasshoppers per square yard

However, the economic importance of an infestation is affected by range condition, cattle prices, and treatment costs.

To find a computer program that can help ranchers estimate their potential damage, as well as a source for maps on grasshopper finds, click here.

Treatments are based on the Reduced Agent and Area Treatment strategy. This method results in untreated swaths and swaths treated with reduced chemical rates. Using lower rates and leaving untreated areas can reduce management costs by as much as 50%, says Gebre-Amlak.