Stop the Japanese Beetle How property owners can help.
LAKEWOOD, Colo. – Thirty-five states to the east of Colorado are currently considered infested or partially infested with Japanese beetle; the Colorado Department of Agriculture is providing valuable tips to homeowners to help protect their property.
The Japanese beetle (Popillia japonica) is an insect pest that is not native to Colorado and can cause significant damage to landscape plants, turfgrass, and fruit trees. Originally introduced from Asia to the Eastern US in the early 1900’s, the beetle has slowly managed to expand its range westward.
This pest is under quarantine in Colorado which is a regulatory activity that limits the transport of goods that spread pests or diseases. CDA, in conjunction with the Colorado Nursery and Greenhouse Association (CNGA) and the US Department of Agriculture, is working diligently to ensure that future introductions of this pest are prevented.
Japanese beetle is most frequently moved from state to state in infested nursery stock and soil. Currently, all trees, shrubs, sod and ornamental grasses brought into Colorado from infested states to the east, must first be certified by the state of origin to be free of Japanese beetle. While it is illegal to knowingly move plants and soil infested with Japanese beetle into the state, it is also illegal to knowingly move plants and soil infested with Japanese beetle within the state
What is a Japanese beetle? Japanese beetle adults are scarab beetles, approximately, one-half inch long with a metallic green body and copper-colored wings. There are five distinct tufts of hair along each side of the beetle’s abdomen. The larvae are white grubs that reside in the soil. Grubs are about an inch long and lie in a curled position or ‘C’ shape when at rest.
What are their favorite plants? Japanese beetle larvae prefer to feed on the roots of grasses, such as those found in lawns or in ornamental beds. The adult beetle has a wide range of plants it prefers including grapes, roses, hollyhocks, black walnut, apples, crabapples, peach, cherry, plum, lindens, mountain ash and lombardy poplar.
How can the beetle be prevented? Purchase landscape plants, trees, and turfgrass only from nurseries, garden centers and landscape contractors that are registered with the Colorado Department of Agriculture. Registered nurseries and sod farms are inspected and nursery stock is verified to be Japanese beetle free. A list of registered nurseries and landscape contractors can be found at www.colorado.gov/ag/dpi  and click on “Nursery Program. ”
Quarantine: Don’t bring uninspected plant materials into Colorado from infested states. Don’t move plants and soil from your property to other portions of Colorado OR to states west of Colorado. This pest is under quarantine and those that bring uncertified plant material into Colorado are subject to fines.
What should one do if they find Japanese Beetle? If you suspect Japanese beetle, collect it and contact the Colorado Department of Agriculture or your local Colorado State University Extension office. The insect’s identity will be verified.
Follow best management strategies to manage the pest by watering your lawn as little as possible, avoid using plants in the landscape that are favored by the pest, and hire a licensed pesticide applicator, if you consider using a chemical control.