Japanese Beetles
These pests remain in the soil for much of their lives. In their underground larval stage, they will feed on the roots of grasses and other nearby plants. Adult Japanese beetles emerge in mid-summer to feed on above-ground plant parts, primary leaves of favored plants. Then the adult female Japanese beetles lay their eggs in the soil in late summer. Moving forward, it is important to understand the signs and best practices from the experts for Japanese Beetle prevention.
Signs of Japanese Beetle Damage
Early Signs
- Dead spots in your lawn or grass around trees and/or bushes.
- Lacy leaves showing up in the upper leaves of some of your trees in the mid-summer.
Late Signs
- Large, lumbering insects flying from tree to tree.
- Lacy, skeleton-like leaves throughout your tree.
For Homeowners
- Adult beetles can be hand-picked off of susceptible plants.
- Contact insecticides can be used to reduce adult foliar feeding.
- Soil treatments can be used to limit turf damage.
- Traps will collect a lot of beetles, however they will also attract beetles to the yard that will feed on trees until they are caught.
For Professionals
- Encouraging homeowners to plant trees that are not preferred by adult Japanese beetles.
- Use appropriate treatments at the proper time for effective results against the beetles.
- Manage and improve tree health to help minimize impacts from beetle damage.
Japanese Beetle Infestation Treatment
Japanese Beetle FAQs
How long do Japanese beetles hang around?
Adult Japanese beetles typically live for up to two months – generally July through August or into September in Wisconsin.
What problems do Japanese beetles cause?
Adult Japanese beetles chew the tissue of leaves, leaving only a lacy-looking leaf.
Are Japanese beetles active at night?
Japanese beetles are not known to be active at night. They prefer the warm temperatures during the afternoon with intense sunlight.