The Colorado Department of Agriculture has joined with local organizations as well as homeowners to eradicate an invasive insect threatening agriculture and tourism in the Grand Valley.

After a Japanese beetle was detected in Grand Junction this summer, the agency has worked to educate homeowners, set up and traps and plan how to prevent the spread of the insect to other areas of Colorado.

“Adult Japanese beetles 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, an 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.”

Over the winter, the CDA will partner the CSU Tri-River Extension Office, Mesa County and the City of Grand Junction to develop an eradication plan. Mesa County will work with the city and homeowners associations to educate homeowners, assist with treatment costs and encourage participation in the plan. 

Pesticide treatments are planned for April to August 2023 with the voluntary participation of homeowners in affected areas. 

In addition, a team will analyze information collected this summer to determine the potential financial effects to agriculture, the costs of the treatment and best management practices to eradicate Japanese beetles.

In the spring, the CDA plans to again place traps in a systematic way to complete a broader delimitation survey and determine if treatment protocols are effective in reducing the Japanese beetle population.

CSU Extension agents in the Tri-River Area also are developing a citizen scientist trapping program for the 2023 season to gather more information about the distribution of Japanese beetles. 

Japanese Beetles were first detected in Colorado in 1995. An exterior quarantine was established in 2009 to prevent the pest from coming into the state. An internal quarantine was added in 2018, to prevent the spread of the beetle from 11 Front Range counties with known infestations. Plant nurseries from outside Colorado and in those counties must perform required mitigation protocols before shipping 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 the Upper Grand Valley Pest Control District (UGVPCD), efforts to eradicate the insect reduced its population by 99 percent 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.”

For more information about the Japanese beetle and its life cycle as well as how to participate in the citizen scientist trapping program, contact the Colorado State University Extension Office at (970) 244-1834. Sightings of the Japanese beetle should be reported by calling (970) 248-7000 or visiting https://ag.colorado.gov/plants/japanese-beetle-in-colorado.