Mesa County Battles Invasive Japanese Beetle: Pest Could Potentially Devastate The Grand Valley's Fruit And Wine Industry

S+B EDITOR'S NOTE: 
In the summer 2023 print issue of Spoke+Blossom, this article incorrectly stated that Bookcliff Gardens caught 239 beetles after setting 123 traps randomly throughout the Appleton neighborhood. Actually, it was the Colorado Department of Agriculture and CSU Extension in Grand Junction who set the traps in northeast Grand Junction. Less than 10 beetles were captured on Bookcliff property where the nursery had set four traps. We regret the error. 

Japanese Beetles have been detected in Grand Junction, where state and county officials fear the insects — if allowed to proliferate — could wreak havoc on the region’s agricultural industry.

The iridescent green beetles love to feed on more than 300 different plant species — including crops like grapes, peaches, roses, sweet corn and turf grass.

“Because the Japanese Beetle affects such a wide variety of plants and can spread through people’s yards, we consider it one of the most damaging insects in the United States,” says Duncan Dearduff, Mesa County’s noxious weed and pest management coordinator.

Thus, Mesa County, the Colorado Department of Agriculture (CDA) and Colorado State University (CSU) Extension-Tri-River Area are working together to eradicate the invasive species and are asking residents for their help in preventing the pest’s spread throughout the Grand Valley.

The Japanese Beetle first arrived to the United States in 1916 when plants infested with the beetle’s larvae were brought from Japan to show in that year’s World Fair, says CSU-Extension entomologist Mel Schreiner. The beetle, which needs moisture to thrive, has spread throughout the humid Eastern and Midwestern United States and has since found habitat in more arid states, like Colorado, due to irrigation.

Although the Rocky Mountains present a natural barrier to the Japanese Beetle — which can fly up to five miles — the beetles have shown up in Utah, California and Washington, Dearduff says.

While no one knows for certain how the Japanese Beetle ended up in the Grand Valley, its larvae most likely hitched a ride on uninspected plant material brought in from out-of-town, Dearduff says. An individual homeowner or unregistered landscape contractor unaware of the beetle problem may have accidentally introduced the pest to the area, he suggests.

Colorado nurseries must register with the CDA, undergo inspections and abide by quarantine rules, Schreiner explains. Buying your plants locally is important for stopping the further spread of the beetle, she adds.

“All of our nurseries [in Mesa County] passed inspections and records checks,”Dearduff says. “There is no evidence that a local nursery brought in the beetle.”

“UNACCEPTABLE RISK”

Mel Schreiner handpicking Japanese beetles off of roses in Littleton, Colorado. Photos courtesy of Mel Schreiner.

The affected area encompasses 24 Road to Horizon Drive and between G and H Roads. Discovery of the infestation is what prompted the CDA, Mesa County and CSU-Extension to develop an early detection and rapid response program. The CDA encourages all nurseries to participate in the beetle trapping program.

State and county officials enlisted the help of residents residing in the “hot zone” by asking permission to spray their lawns for free with the insecticide Acelepryn. The pesticide kills the grubs (the larval stage of the beetle) before they hatch but is considered safe for pollinators, shares Dearduff. It’s a long-lasting grub control classified by the EPA as a “reduced risk pesticide,” he says.

As a precaution, those who reside outside the known infested area are encouraged to treat their property on their own with a granular product called Grub-ex, available at area plant nurseries and hardware stores.

Nationally, the Japanese Beetle causes $460 million in damages each year. Mesa County Commissioner Cody Davis says there’s an “unacceptable risk of the pest spreading across Mesa County and local produce [having to be]quarantined, which would severely affect our local economy.”

Peaches generate approximately $14 million annually for Mesa County; wineries and vineyards bring in about $40 million each year; Palisade Fruit and wine-associated tourism brings in $22 million per year.

It’s not the first time the Japanese Beetle has attempted to find a home in the Grand Valley. In 2002, a CSU master gardener spotted the insect in Palisade, which sparked an aggressive eradication campaign, Schreinerre calls. Agriculture and tourism are crucial to Palisade’s culture and economy.

It took six years, from 2003 until 2009, of aggressive actions to reduce the number of beetles in Palisade from nearly 1,300 to zero, Schreiner says. Palisade already had a pest district with funding in place to deal with the problem quickly.

Japanese beetle adults feed and reproduce in masses, which can increase damage.

BEETLE HOTLINE

The Japanese Beetle has a lifecycle of one year, beginning with beetles laying eggs in turf grass in August and September, where they remain dormant during winter. The larvae wake up in April and May, and start munching on the grass roots.

In June, the grubs hatch and make cocoons before the beetles emerge in July when they begin attacking plants, like roses and fruit, and start laying eggs.

“The adults come out of the ground and start eating plants; they skeletonize leaves,” says Mona Dyer, a Colorado-certified nursery professional who has worked at Bookcliff Gardens for 19 years.

“We want people to understand there could be a Japanese Beetle in their yard, but they won’t see it until July,” she says. “But, you can get ahead of it by putting Grub-ex on your yard in April and May.”

“We want people to understand there could be a Japanese Beetle in their yard, but they won’t see it until July,” she says. “But, you can get ahead of it by putting Grub-ex on your yard in April and May.”

And, while you can try trapping or picking off the beetles if you spot them on your property, the potential impact the insect poses to the Valley’s fruit, wine and tourism industries has prompted local officials to vigorously tackle the problem by killing the pests before they hatch.

“Picking off adult beetles is just a Band-aid; grubs must be controlled,” Schreiner warns.

“Eradication of the beetle in Grand Junction will require everyone to be on board,” Dearduff adds. “You’re not only protecting your own lawn but all of Mesa County and the Western Slope.”

Mesa County has set up a Japanese Beetle Phone Tree hot line to answer people’s questions about the bug. When residents call970.248.7000, they will be directed to either the CSU Extension, the CDA or the Mesa County Noxious Weed and Pest Control — depending on the question.

“So much is at risk here in Western Colorado,” Schreiner says. “There are a lot of tree fruits, onions, corn. It’s all threatened if we have an established population herein Colorado. There’s a great amount of fear around this.”