Keeping Japanese beetles at bay can be a losing battle. Controlling these pests is challenging for even the most seasoned gardeners.
So what’s a homeowner to do?
Creating a habitat that is less suitable for Japanese beetles might be your best bet.
Specifically, carefully selecting plant species when replacing or adding to your landscape could be the key to avoiding an annual battle with Japanese beetles.
Although Japanese beetles feed on about 300 species of plants, they feed sparingly or not at all on many common trees and shrubs.
These include: red maple, silver maple, boxwood, flowering dogwood, euonymus (all species), white ash, green ash, holly (all species), tuliptree, magnolia (all species), red mulberry, white poplar, common pear, white oak, scarlet oak, red oak, black oak, rhodendron, American elder and common lilac.
Likewise, most evergreen ornamentals, including Abies (fir), Juniperus, Taxus, Thuja (arborvitae), Rhodendron, Picea (spruce), Pinus (pine) and Tsuga (hemlock) are not attacked.
Boxelder, shagbark hickory, persimmon and American sweetgum are also options but may suffer occasional light feeding.
Plants to avoid using in your landscape include: Japanese maple, Norway maple, horse chestnut, hollyhock, gray birch, American chestnut, Rose-of-Sharon, shrub althea, black walnut, flowering crabapple, apple and London planetree.
Also avoid, if possible: Lombardy poplar, cherry, black cherry, plum and peach trees, rose, sassafras, American mountain-ash, American linden, American elm, English elm, and table grapes. These plants are nearly always severely attacked by Japanese beetles.
You might find it surprising that Japanese beetles are also fond of certain weeds and noneconomic plants such as multiflora rose, Indian mallow, poison ivy, smartweed, and wild summer grape. If you get rid of these plants, you likely eliminate a continuous source of infestation.
For more information on this topic, refer to UKY publication “EntFact-451 Japanese Beetles in the Urban Landscape,” which can be found at http://www2.ca.uky.edu/entomology/entfacts/ef451.asp or stop by the county office for printed copy.
For other horticultural questions, contact the Franklin County Extension Office, 502-695-9035, or Adam.Leonberger@uky.edu.
Source: Lee Townsend, UK entomologist