Japanese beetles are disgusting in all their forms—grubs and adults. I shudder every time I find one of those yucky white grubs curled up in my soil. And I freak when I find hordes of adults munching away on foliage and flowers. There’s something about the hard metallic look of their little bodies that gives me the creeps.
But the worst part is not their looks—it’s their ability to wreak havoc in the garden. Those little devils can defoliate a plant in record time. And did you know that grubs overwinter in the soil and damage lawns by feeding on grass roots as they head to the soil surface to become adults?
Expect adult beetles to emerge in late June, bent on destruction. Look for swarms of adults on your favorite plants in July. Some of the adult’s 300 favorite edibles include flowering cherry, flowering crabapple, linden, elm, birch, roses, zinnias, Virginia creeper, Boston ivy, Canna, Rose of Sharon and marigolds. I suspect they’re like deer—they’ll eat anything if they’re hungry enough.
Adult Japanese beetles like hot weather and full sun. That’s why I make beetle rounds at 12 Noon on sunny days. I shake beetle-encrusted leaves over a jar of soapy water, which results in the end of their eating orgy and their ultimate death.
If you prefer to use insecticides, apply according to label directions from late June through July when adults first appear and before damage occurs. If repeat applications are needed, read and follow label directions.
Be very careful when using pesticides. Here’s a warning from Penn State Extension: Pesticides are poisonous. Read and follow directions and safety precautions on labels. Handle carefully and store in original labeled containers out of the reach of children, pets, and livestock. Dispose of empty containers right away, in a safe manner and place. Do not contaminate forage, streams, or ponds.
Since my land is a certified wildlife habitat, I prefer a more natural approach—milky spore powder or beneficial nematodes. These natural alternatives to pesticides are not harmful to beneficial insects, birds, bees, pets, people or water.
For more information, go to PSU’s Japanese Beetle Fact Sheet
Do you have a gardening question? In Delaware County, call our Master Gardeners hortline at 610-690-2671 on Tuesdays and Thursdays from 9 AM-12 NOON.
UPCOMING MASTER GARDENERS EVENTS
April 26, 2008
Arbor Day Celebration
Join us at Smedley Park for an afternoon of educational activities for children that are designed to stimulate interest in trees and the environment. We'll provide hands-on experience in planting trees. Contact Elsie Mueller at 610-626-7210 or email for more information.
May 10, 2008
Invasive Plants
Learn to recognize and control plants that have been introduced to the USA and are now taking over our landscapes. We'll suggest alternative native plants to use in place of those aggressive invasives. Cost: $10
Registration required for all events except Arbor Day. Please call 610-690-2655 for more information or visit our website for a registration form.
