Japanese beetle detected on Western Slope in Colorado | TheFencePost.com

Japanese beetle detected on Western Slope in Colorado

State and county take measures to eradicate pest

GRAND JUNCTION, Colo. — After a detection of the invasive Japanese beetle in Grand Junction, Colo., this summer, the Colorado Department of Agriculture has been working in partnership with local stakeholders to eradicate the pest and prevent its spread into additional areas of Colorado.

“CDA has been working with our partners in Mesa County’s Noxious Weed and Pest Management programs and with the Colorado State University Tri-River Extension office to educate homeowners in the Grand Junction area about the detection of the Japanese beetles and to set up traps in the affected areas,” said Rich Guggenheim, Ph.D, Plant Health Certification Program manager at the Colorado Department of Agriculture. “Over the next few months we will be formulating a plan on how to work with the community to eradicate this invasive pest that is a threat to the region’s agricultural and tourism economies.”

The beetle is a known pest and a quarantine is in place to prevent its spread into areas without current infestation, including the Western Slope.

“Adult Japanese beetle are voracious defoliators that feed on more than 300 species of plants, many of which are essential to western Colorado’s agricultural economy, including peaches, grapes, sweet corn, turf, and many other ornamental plants in urban spaces,” said Melissa Schreiner, entomologist with the Colorado State University Tri-River Extension Office. “Adult beetles feed on leaves, flowers, and fruit of trees, shrubs and perennials while the larvae are serious pests causing root damage to turf grass. We will be working to educate people in the affected area about how to identify and help eradicate this invasive pest.”

Figure A: Japanese beetle life cycle, image produced by University of Minnesota ExtensionFigure B: Photo of Japanese beetle adults feeding on a rose flower. Photo by Melissa Schreiner

Japanese Beetles were first detected in Colorado in 1995 through trapping and Colorado’s Exterior JB Quarantine was established in 2009 to prevent the pest from coming into the state and spreading to areas without current detections. An internal quarantine was added to the JB Quarantine in 2018, to prevent the spread of the beetle from 11 counties on Colorado’s Front Range known to either be partially or totally infested with JB. Plant nurseries in those counties, as well as any out of state, must perform required mitigation protocol before being allowed to ship plants into or to other parts of Colorado.

On the Western Slope a Japanese beetle was discovered by a Master Gardener in 2002. According to data from the Upper Grand Valley Pest Control District, the area around the UGVPCD acted decisively to eradicate the pest and reduced its population by 99% over five years.

“CDA has been trapping and monitoring the Japanese beetle population in our region for 20 years to assist the Upper Grand Valley Pest Control District. This summer, with a detection of a reproducing population, the county partnered with CDA in setting up additional traps to identify the area where the beetles have concentrated,” said Duncan Dearduff, Mesa County Noxious Weed and Pest Management coordinator. “Japanese beetles will devastate ornamental plants and turf across the Grand Valley. We’ve eradicated this pest before and with strong support from our neighbors and the agricultural community our goal is to eradicate it from Mesa County once again.”

Over the winter months, CDA will partner with Mesa County, City of Grand Junction, and CSU Tri-River Extension Office to draft a plan for eradication of the beetle. Mesa County will work with the City of Grand Junction and homeowners associations in the area to educate homeowners, assist with treatment costs, and encourage participation in the plan. Pesticide treatments will take place from April-August of 2023 with the voluntary participation of homeowners in the affected area.

Additionally, the team will analyze the data collected this summer to determine the financial impacts to agriculture, the costs of the treatment, and to develop the best management approach with the goal of eradicating the pest. In the spring of 2023, CDA will again place traps in a systematic way to complete a broader delimitation survey, determine if the treatment protocols are effective, and to see if there is a reduction in the beetle population. CSU Extension agents in the Tri-River Area are developing a citizen scientist trapping program for the 2023 season with the goal of gathering more data from citizens on the distribution of Japanese beetles in our area.

People who live in Mesa County are encouraged to monitor their plants and turf for the presence of the Japanese Beetle. Any sightings of the pest should be reported to the Japanese beetle helpline at (970) 248-7000 or https://ag.colorado.gov/plants/japanese-beetle-in-colorado.

Questions about the Japanese beetle, its life cycle, and how to participate in the 2023 citizen scientist Japanese beetle trapping program can be directed to the CSU Extension office at (970) 244-1834.


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