"They eat some bad plants, but they eat a lot of good ones too, like our harvest," says Renfro.
The crickets are spreading in huge numbers across southern Idaho, Utah and Nevada, reports CBS News Correspondent John Blackstone.
Some blame the long drought in much of the interior West for the outbreak. It's been 60 years since crickets showed up in these numbers.
Their voracious appetites take in anything - sagebrush, alfalfa, wheat, barley, clover, seeds, grasses, vegetables. At a density of just one cricket per square yard, they can consume 38 pounds of forage per acre as they pass through an area. They don't fly, but can hop and crawl a mile in a day and up to 50 miles in a season. And before they die in the fall, they lay the eggs that will become next year's swarm.
The Mormon cricket actually is a katydid, similar to a grasshopper. It got its name in 1848 when swarms invaded the fields of Mormon settlers in Utah. According to lore, the settlers prayed for divine assistance that arrived in the form of gulls, which ate the insects and saved the crops.
Its come to the point that on Highway 55 the Idaho Department of Transportation has put up warning signs cautioning drivers that the roads can be slippery – with crickets.
When the marching crickets meet the pavement, drivers should know it's not just the insects that are in peril.
"If they hit these crickets in a bad way it's worse than black ice," says Fawn Carey, disaster coordinator for Boise County, where the crickets have been declared a disaster.
In some places around Boise it's hard to escape crickets right now. A day at the lake, a picnic in the park can be disturbed by much more than ants.
"They're red, brown and scary, and they jump very high," says one giggling young girl.
This cricket population explosion started last summer when there were so many crickets at Lucky Peak reservoir nobody wanted to set foot on the dock.
To save their crops, ranchers like Mike Renfro are using poison bait to kill off the crickets. But every female that lives can lay more than 75 eggs to hatch next year.
The bad news is that no matter how many are killed, these bugs are true survivors. Archeologists have found evidence that cricket infestations have been a regular part of life in the West for more than 2,000 years.