Plant Tolerance of Japanese Beetles
E = evergreen; N = native to Maine
|Trees Not Preferred by Japanese Beetles:|
|Abies species E, some N||Fir|
|Acer rubrum N||Red Maple|
|Acer saccharinum N||Silver Maple|
|Fraxinus americana N||White Ash|
|Fraxinus pennsylvanica N||Green Ash|
|Pinus species E, some N||Pine|
|Quercus rubra N||Red Oak|
|Thuja occidentalis E, N||Arborvitae; White Cedar|
|Tsuga canadensis E, N||Canada Hemlock|
|Shrubs Not Preferred by Japanese Beetles:|
|Juniperus species E, some N||Juniper|
|Ilex species some E, some N||Holly|
|Taxus E, some N||Yew|
|Perennials Not Preferred by Japanese Beetles:|
|Aquilegia species some N||Columbine|
|Dianthus species E||Pinks|
|Lilium species some N||Lily|
|Viola species some N||Viola, Violet|
|Annuals Not Preferred by Japanese Beetles:|
|Plants Very Frequently Attacked by Japanese Beetles:|
|Acer palmatum||Japanese Maple|
|Betula populifolia N||Gray Birch|
|Malus cultivars||Crabapple; Apple|
|Prunus species some N||Cherry, Plum|
|Tilia americana N||Basswood|
|Preferred Hosts of Japanese Beetles:|
|Betula species some N||Birch|
|Vitis species some N||Grape|
White Grubs in Maine Lawns
Six species of white grubs occur in Maine. They are the ground-dwelling larvae of these insects:
- Japanese beetle
- European chafer
- Oriental beetle
- May beetle (also called June beetle)
- Asiatic garden beetle
- Rose chafer
To scout for white grubs, which feed on plant roots:
Use a shovel to cut three sides of a 12” square in a lawn. Grab the open edges and peel back the square of turf like a carpet. Look for C-shaped white grubs on the newly exposed soil. Sample several places.
When to do something about white grubs:
If there are fewer than 5 grubs per square foot: don’t treat.
If there are 6-9 grubs per square foot: An otherwise healthy lawn can tolerate this level of grubs. However, if skunks, raccoons, birds and moles are digging to find the grubs, you may wish to treat areas with high numbers of grubs.
If there are more than 10 grubs per square foot: you may wish to treat.
Treatment products and timing vary, depending on type of grub. Call your UMaine Extension county office for advice.
From the GardenPro Answer Book; revised and updated by Lois Berg Stack, Ornamental Horticulture Specialist, University of Maine Cooperative Extension.