Japanese beetles

Bulletin courtesy photo by Colorado State University In August, Japanese beetles were discovered in Sheridan County. This pest is considered to be an invasive species and feeds on the leaves, flowers and fruit of more than 300 plant species.

For someone well versed in weeds and pests, Rod Litzel has surprisingly little to say about the Japanese beetles recently discovered in Sheridan County.

There’s a reason for that. Litzel, the Johnson County Weed and Pest supervisor, has never encountered a Japanese beetle out in the field. He’s researched the insect online and has occasionally encountered one of the beetle’s close cousins, the June beetle. But the Japanese beetle has remained clear of Johnson County so far.

That could change in the near future, Litzel said. With 250 Japanese beetles discovered in 43 acres of Sheridan County, the insects are just a short flight away from devastating the flora and fauna of Johnson County.

“They are very capable flyers,” Litzel said. “If they decide to pick up and move, it’s only a matter of time before we start dealing with them here. If they’re going to migrate in this direction, there’s nothing we can do to stop them.”

Japanese beetles generally grow to 0.6 inches in length and 0.4 inches in width. They are a metallic green color with bronze wing covers. The beetle was first detected in New Jersey in 1916 and has gradually spread across the country. Sheridan County is the first known location of adult Japanese beetles in the state of Wyoming.

The beetles have an impact on both turf and trees, depending on their life stage.

When the beetles are in the larva stage in spring, they live in moist soil underneath grass. They  feed on the roots of the grass, effectively killing large swaths of it in the process.

“A sign that you have Japanese beetles is that you will have pretty big, brown patches of turf,” Litzel said. “If you grab the dead area, it will just come up in one piece.”

When the beetles make mature to adulthood, they no longer eat grass roots, but instead target leaves of a variety of trees including linden, crabapple, chokecherry, birch, buckeye and willow trees.

“The adults do even more damage than the larvae,” Litzel said. “They can be pretty devastating.”

According to Litzel, the Japanese beetle is not a declared pest species in Johnson County, which means that Weed and Pest will not immediately expend dollars on controlling the species if it is found in Johnson County. What they will do, Litzel said, is help landowners identify the beetle while offering advice on mitigation measures that landowners can pursue including pesticides and traps.

“There is not one specific remedy,” Litzel said. “How we address the problem kind of depends on the goals of the landowner and whether they want to pursue organic or chemical solutions. So our role is developing a control strategy in consultation with the property owners.”

The Sheridan City Council unanimously passed a resolution last week asking all Sheridan residents and businesses to immediately stop watering lawns, green spaces and gardens for the remainder of the season to create conditions that make it harder for the beetles to survive.

The city has also set traps in parks and green spaces to get a better estimate of the beetle population.

Litzel said that, because the beetles have never been in Wyoming before, a lot of questions are sparked by their arrival. He said that Weed and Pest remained committed to partnering with landowners to answer those questions as they arise.

“We are happy to provide consultation services and kind of walk with landowners through this process,” Litzel said. “I think the big takeaway right now is that we’re willing to work with them and help them identify these beetles if they arrive in Johnson County.”


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