Experts expect 15-plus grasshoppers per square yard to swarm Colorado county

The risk for grasshopper outbreaks will be low for much of Colorado this summer, save some regions of Routt County where the U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) has forecasted 15-plus grasshoppers to be present per square yard of outdoor space. 

The prediction was laid out in the service's 2023 Rangeland Grasshopper Hazard Survey, which analyzed data from adult grasshopper specimens in fall of last year. 

As illustrated on the map below, a large portion (the area shaded in red) of Routt County could be impacted. 

According to the USDA, not all grasshopper infestations or outbreaks call for management, because not all grasshopper species significantly damage rangelands. However, mitigation could be necessary if grasshopper populations threaten rangeland forage. 

In a report by Colorado State University, researchers stated that local outbreak mitigation techniques typically include using sprays or baits to kill the insects. 

"Grasshoppers can be the most noticeable and damaging insects to yards and fields. They also are among those most difficult to control, since they are highly mobile. For many reasons, grasshopper populations fluctuate greatly from year to year, and may cause serious damage during periodic outbreaks," the report reads. 

Still, the current grasshopper forecast is not necessarily set in stone. Weather could still change the outcome of grasshopper hatches. 

"For example, cold, wet weather is very destructive to newly hatched grasshoppers. However, very dry winter and spring conditions also can be harmful to survival since required tender new plant growth is not available," the CSU report reads. 

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