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Anabrus simplex is the Latin name for the shield-backed katydid. The insects have hatched in Rio Blanco County and are moving in bands through fields, across roads, and in crops. Commonly known as the Mormon cricket, outbreaks are more common in Nevada and Utah, but they’re found throughout the Western U.S. They hatch once a year, sometimes once every other year at higher elevations and have an adult life span of about 20 days. 
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Rio Blanco County has an outbreak of Mormon crickets

The ground looks like it’s alive at the McKee ranch northwest of Meeker, where an outbreak of “Mormon crickets” is on the march. In the late afternoon and early evening, the insects, which are up to 3 inches long, cover the driveway, climb the side of the house and cover the trunks of the trees in the yard. 

According to Dr. Whitney Cranshaw, extension specialist for Colorado State University, “Those are definitely Mormon crickets. Dark phase, which is the phase when they wander about sometimes in bands.” 

The McKees, who grow alfalfa, brome grass, triticailia and spring wheat, are concerned about crop damage as the voracious insects make their way across the property. They’ve reached out to the county and the local extension office for help, and bought pesticide granules and spray, but for now, the bugs are eating their way through the ranch. 

McKee said it’s the first time she has seen an outbreak of so-called Mormon crickets on their property but is aware of an outbreak years ago at the Keystone ranch. Comments on a social media post from the Extension office indicate multiple swarms in varied locations. 

Outbreaks were reported in Nevada, Utah and Idaho back in February and March in what was referenced as an unusually early hatch. According to a report from the University of Nevada at Reno, drought encourages the outbreaks, which may last several years.


Michelle Cox Photography

So what are these insects locals call Mormon crickets? 

Their Latin name is Anabrus simplex. They’re actually a shield-backed katydid of the Tettigoniidae family, which includes certain kinds of grasshoppers.  According to CSU Extension, they are native to the western U.S., and can be found in “the open sagebrush/grassland rangelands of the Colorado Plateau and Great Basin at elevations between 6,500 and 11,000 feet.” 

The insects, which can grow to almost 3 inches in length, lay their eggs underground. Those eggs hatch in the spring when conditions like soil temperature are right. 

Once they hatch, they start to eat. According to a University of Wyoming fact sheet, “Feeding tests demonstrate that during its nymphal period and 20 days of adult life, an average Mormon cricket consumes 3,518 mg of vegetation (dry weight). Calculations based on this figure indicate that at a density of one per square yard the Mormon cricket consumes an amount of rangeland forage equal to 38 pounds dry weight per acre. Because of their migratory habit, Mormon crickets may be present in a particular site for no more than three or four days. In this short time, their damage to rangeland is perceptible but not measurable by standard quantitative techniques.” 

Unlike locusts, Mormon crickets can’t fly, but they can march. Up to a mile or more a day, according to a 2005 study. 

Dr. Bob Dorsett of Meeker said via email, “Now and again our critters swarm, different populations marching in large numbers across their range.  There’s evidence the swarms may be forced marches driven by resource depletion and cannibalism, and swarming may protect individuals from cannibals and other predators. We see swarms every few years especially out around Dinosaur and Jensen.” 

As they move, they damage crops and can become a road hazard. There are reports of so many insects crushed by cars, and then other insects swarming the road to cannibalize the dead ones, that the roads get slick.  

These misnamed katydids have their place in Mormon history, which is where they earned the “Mormon” moniker. A statue of a seagull at the LDS Temple Square in Salt Lake City memorializes the “Miracle of the Gulls,” a tale from 1848 when white gulls swooped in and gobbled up swarms of the insects, who were eating the crops of starving Mormon pioneers. 

In 1927, an outbreak in Northwest Colorado destroyed 1 million acres of Colorado crops. An essay by Routt County rancher-politician-storyteller Farrington Carpenter describes the crickets as “the most feared insects in the Rocky Mountain area.” 

Carpenter also wrote that noise was one way to drive the insects away. “The only protections against these marauders was noise. Many settlers protected their gardens or small fields by ringing cow bells, sleigh bells; pounding on tin buckets or rattling tin cans on a wire. This would cause an oncoming band to divide and go around the hubbub.”

According to Carpenter, county commissioners in Routt County devised another method that proved effective: 10 miles of 18-inch rolls of tin were used to create a “fence,” with pits dug every few hundred feet to trap the insects.

By NIKI TURNER | editor@ht1885.com