The 2010 grasshopper hazard map, based on last year’s survey of adult grasshopper activity, shows a greater than normal risk for outbreaks for these pests in some northeastern Colorado counties.

Created by USDA, the map may be viewed at http://www.sidney.ars.usda.gov/grasshopper/Extras/map10.htm.

This site also offers additional grasshopper information.

Higher risk of grasshopper infestation is predicted for Yuma and northern Kit Carson counties. Other counties with more localized area of high risk include Washington, Morgan, Logan, Lincoln, El Paso and Weld, reports the Colorado State University Extension Service.

Weather conditions will determine how much of the potential will be realized, adds CSU.  For example, cool and wet conditions after hatch can result in enough pest mortality in immature grasshoppers to prevent an outbreak. In addition, if adequate moisture is available, forage growth will offset much of the grasshopper damage. Most outbreaks occur when drought conditions are present.

Landowners in high risk areas should start monitoring populations in rangeland as soon as possible, urges CSU. Start looking for the pests after grasshopper hatch, primarily during June. Early scouting is important because treatments are most effective when grasshoppers are small. The goal of monitoring is to get an estimate of grasshoppers per square yard, as well as their stage of development.

The economic threshold for grasshoppers in rangeland is 15-20 nymphs per square yard. This number is equivalent to eight to ten adult grasshoppers per square yard.

However, the economic importance if an infestation is affected by such factors as range conditions, cattle prices and treatment costs, notes CSU. 

Yuma County Pest Control District officials are looking for landowners and aerial applicators to participate in a coordinated management program. To take part, call (970) 848-2509.