CDA: Significant Decline in Mesa County Japanese Beetle Population
Colorado Department of Agriculture (CDA)
After a successful summer treatment plan, Mesa County and the city of Grand Junction are celebrating an 85% reduction in Japanese beetle populations. Found in the city of Grand Junction in the summer of 2022, Mesa County declared the beetle a public nuisance species in March 2023. Joined by the Colorado Department of Agriculture (CDA), CSU Extension, and the City of Grand Junction, Mesa County has worked to eradicate the species, which is a threat to both crops and ornamental plants on the Western Slope.
“We saw a significant reduction in the number of beetles we found through our trapping efforts,” said Wondirad Gebru, Director of the Plant Industry Division at CDA. “Through our collaborative efforts with fruit producers, CSU Extension, and the City of Grand Junction, we’re seeing great success in the treatment plan implemented by Mesa County.”
The eradication of the pest is a multiyear project and started in July 2023. The first treatment was applied in Spring 2023. After the second full year of treatments, CDA trapped 830 beetles in or near the treatment area, down from 5,716 in 2023.
“Thanks to the dedicated efforts of our Mesa County Noxious Weed and Pest Management team, our partnership with the City of Grand Junction, Colorado State University Extension Office, and the generous support of the Colorado Department of Agriculture, we are proud to report such a significant reduction in Japanese beetle numbers in Mesa County,” said Mesa County Commissioner Bobbie Daniel. “The 85% decrease in the beetle population is a testament to the effectiveness of our targeted treatment strategy and collaborative approach. We remain committed to closely monitoring the data and aggressively treating hot-zone areas to safeguard our region's agriculture and economy against this destructive invasive pest.”
In 2024, CDA provided a one-time grant of $110,000 to Mesa County to help cover the cost of the treatment. The Japanese beetle is an invasive pest which can cause tremendous damage to western Colorado’s agricultural economy, including peaches, grapes, sweet corn, and other crops. The beetle can be found on more than 300 species of plants, including ornamental plants in urban spaces, including turf grass and decorative flowers.
Mesa County already beat back a Japanese beetle infestation in the early 2000s. The beetle was discovered by a Master Gardener in the county in 2002. According to data from the Upper Grand Valley Pest Control District (UGVPCD), the area around the UGVPCD acted decisively to eradicate the pest and reduced its population by 99% over five years. Due to quick and decisive action, the pest did not cause significant damage to fruit crops grown in the region.
To protect the state's fruit and wine industry, a quarantine is in place that prevents the import of commodities that carry the Japanese beetle from affected areas, including the Front Range, to areas not under quarantine, such as Mesa County. The Pest Control Act gives CDA the authority to establish an intrastate quarantine to restrict the movement of nursery materials to prevent the spread of pests.
In addition to fighting invasive pests, CDA’s Plant Industry Division provides a broad array of programs and services related to crop production, environmental health, and export certification. The division regulates hemp producers, nursery and seed distributors, organic producers, plant imports, and more.
Read the original press release.
