Mesa County Warns of Codling Moth Threat to Apple Harvests

GRAND JUNCTION, Colo. — Mesa County agriculture authorities are warning of an impending threat to apple and pear crops this summer as codling moth larvae, a notorious orchard pest, begin to emerge in the Upper Grand Valley.

The Upper Grand Valley Pest Control District, Colorado State University Tri-River Extension, and Mesa County officials are partnering to alert fruit growers and backyard orchardists alike of the dangers posed by the codling moth—a small but destructive pest whose larvae burrow into fruit, making it unmarketable and inedible.

Larvae Pose Summer Threat

The codling moth’s larvae, light pink or white in color, are most active in early summer. Once hatched, the larvae bore into apples or pears, feeding on the flesh and leaving a signature brown trail of frass, or insect waste. The result is not just ruined fruit, but potential economic losses for growers and damage to regional fruit quality.

“One abandoned orchard or somebody not playing their part affects everybody,” said Jeff Pieper, commercial horticulturist and natural resource specialist with CSU. “That can be homeowners who just aren’t aware.”

Community-Wide Responsibility

Experts are emphasizing that even individual homeowners with a few trees in their yard can unwittingly contribute to the infestation problem. If unmanaged, these trees become breeding grounds, enabling moths to spread into neighboring commercial orchards.

To counter this, Pieper recommends installing pheromone traps, which lure male moths and serve both as detection tools and population control methods. Additionally, growers should thin fruit clusters to avoid touching apples—creating less ideal environments for moths to lay eggs—and consider bagging individual apples in protective paper coverings to prevent infestation.

Why It Matters

Mesa County’s apple and pear harvests are a key component of the Grand Valley’s agricultural economy, which supports local markets, cider production, and agritourism. A severe codling moth outbreak can lead to thousands of dollars in crop losses, increase the need for chemical spraying, and disrupt supply chains to local produce stands and processors.

In past years, unmanaged urban orchards and abandoned properties have exacerbated regional infestations, leading to calls for stricter pest management awareness among residents.

What’s Next

Agricultural officials plan to distribute educational resources to homeowners this month and encourage the use of low-impact control strategies. Extension officers will also monitor regional pheromone trap data to assess codling moth population surges as summer approaches.

Residents are advised to contact the CSU Tri-River Extension Office for guidance on safe treatment methods and trap installation.