Farmington, Minnesota

Photo by Jason Jensen

Japanese Beetles

Japanese Beetles
Posted on 07/10/2018
Japanese BeetlesJapanese beetles have been observed in high concentrations in Farmington, and the city wants residents to know how to combat them.

“Due to the wet spring and warm temperatures, the beetles are having another year of high population,” said Public Works Project Coordinator Tom Hoffman. 

Japanese beetles are an invasive tree pest that feed on the leaves and flowers of numerous trees and plants, including ornamental roses and fruit trees. During years of high population, they can defoliate entire areas. Fortunately, the beetles rarely cause mortality and plant species are typically able to rebound the following year. However, continuous feeding in subsequent years can weaken plants and trees and make them more susceptible for mortality.

Homeowners can hand pick the pests from plants, or shake them off into a pail of soapy water. This method is not feasible for mature trees or areas of high infestation. Homeowners can also contract a plant management company to complete an insecticide treatment to protect specific plants or plants in areas of high beetle concentrations. Treatments should be done by a professional to limit the impact and spread of the chemical.

Japanese beetles emerge from the ground in early summer. Luckily, they have a short life cycle and will start to decrease in numbers by mid-August. It is not recommended to use traps to catch the beetle. Although traps may catch an impressive number of beetles, they attract beetles from other areas using scent. Studies have shown areas with the traps have had more damage than neighboring areas.

Japanese beetlesNatural resources

The University of Minnesota is a great resource for more information on Japanese beetles. Read its web page that gives the history of the Japanese beetle, the damage they cause and more information on how to reduce them.

For more information, contact Hoffman at or 651-280-6845.