There is no denying it now. The Japanese beetles have made their yearly return to aggravate area gardeners. One beetle won't do a lot of damage, but as we know they often don't come alone. Large groups of feeding beetles will start at the top of a plant and work their way down. The early arrivals release hormones that attract others to the plants. In addition the females release sex pheromones, attracting males to the area. Odors released from the beetle-damaged leaves also assist in attracting more beetles to the area.
One way to control Japanese beetles is to not plant trees and shrubs the beetles like to eat. This list includes Japanese and Norway maples, birch, pin oak, rose of Sharon, apples, plums, cherries, roses, willows, lindens, hollyhock, grapes, and even poison ivy! Removing them by hand does help since the beetles attract beetles. You can hand pick, hose them off, or shake the plant over a bucket of soapy water. Early morning is a great time to work since the beetles are sluggish. Highly valued plants can be covered with row cover or even cheese cloth.
There are chemicals that can be used on Japanese beetles. If you do use this route, make sure to thoroughly read the label and follow the instructions. This is especially important if you are spraying anything you wish to later eat. Remember all insecticides can harm bees, so do not spray plants with open flowers.
Many people love to use the Japanese beetle traps on the market. Unfortunately, these can draw thousands of beetles to the area each day and research has shown these traps attract more beetles than are caught. If used, your plants could suffer more damage than if no traps had been used!
The other method that does not offer full control is grub control. While it is true beetle grubs do feed on your lawn's roots, using grub control does not guarantee the beetles will not fly in from a neighboring area. Grub control should only be used as a way to control grub damage.
Fortunately, the beetles are with us for only a few weeks each year. Adults only live for about 30-45 days. My advice is to find some kids, give them a jar of soapy water, and send them out each morning.
Anne Lenox Barlow has had experience in the agricultural field as a horticulture educator with Cornell Cooperative Extension in Clinton County. She can be reached by e-mail at firstname.lastname@example.org.