Japanese Beetle in Colorado
The Japanese beetle is an invasive pest that was introduced into the eastern United States over 100 years ago. Since the early 1900s, the insect has made its way West, moving long distances in nursery stock (root balls of trees, shrubs, and turfgrass plants) sold in trade and about 1 to 5 miles per year on its own from plant to plant.
The Japanese beetle was first introduced into Colorado in the early 1990s from nursery stock purchased in the mid-western United States. Scientists and experts were caught off guard by the ability of the pest to establish itself in our region, thinking that Japanese beetle, an insect that likes moisture and humidity would never become a problem in the semi-arid Colorado climate. However, our urban landscape areas are oases of green, irrigated plant material that the beetle loves to eat and thrive in.
Precautions need to be taken to keep this pest from spreading to noninfested areas of the State. Why? Japanese beetle adults are voracious feeders and cause significant damage to over 300 different plant species found in our landscapes, our agricultural areas, and a few of our native plants as well!
For commercial nurseries and garden centers in Colorado, Japanese beetle becomes a pest that is regulated. Colorado Nursery law prohibits the sale of plants containing Japanese beetle adults or larvae in the root zone. There is zero tolerance for this pest as it has high economic consequences for nurseries who export stock to western states. Nurseries and sod farms on the Front Range can serve as sources of introduction to un-infested areas. For nurseries and garden centers known to have Japanese beetles present, constant management is required.
For homeowners, landscape managers and Colorado agriculture producers this pest is also devastating. Damage done to ornamentals, grasses and fruit crops in Colorado can be significant. Integrated control strategies are highly encouraged.
Over the past 9 years, Colorado Department of Agriculture has focused its Japanese beetle prevention efforts on an external quarantine and monitoring nursery stock imported into Colorado from the midwest and eastern US sources. While mostly successful, in 2017 with the Nursery Industries’ support, the first internal quarantine of a Japanese beetle infested area within the State of Colorado was adopted. We must work together to expand our focus on the potential movement of this insect from the Denver metro area to other un-infested areas of the State.