Controlling Japanese Beetles

Japanese Beetles (Popillia japonica Newman) are a non-native invasive pest that is found in every state east of the Mississippi River. Arriving in the US on imported plants from Japan in 1916, the Japanese beetle has no natural enemies in the United States.

Japanese beetles are about half an inch long and have copper colored wings over a metallic green body. These beetles eat the leaves of many plant species, leaving only a leaf skeleton behind. The grubs of Japanese beetles eat the roots of grass and can cause widespread turf damage.

The Organic Approach
There are several organic methods for controlling Japanese beetles:

• Get -em while they're young. Applying Milky spore (Bacillus popillae) to turf is a good way to control Japanese beetle grubs. The grubs eat this bacterium and when it kills them, more spores are introduced into the dirt. Milky spore may take two to fours years to treat a yard and is most effective when it is applied neighborhood wide.
• Take in the welcome mat. Beginning in June, look for individual Japanese beetles. Remove them from plants by hand and dump them in a bucket of water mixed with ¼ of dishwashing soap. Place the bucket near plants you want to save or an area of your garden that gets good ventilation. Japanese beetles use scent to look for places to eat. Your "bucket of doom" will go a long way toward controlling Japanese beetles in your garden.
• Fight back with plants. Japanese beetles aren't big fans of catnip or tansy. Planting these plants in the garden near vulnerable plants will keep beetles at bay. Rue and garlic are also plants that Japanese beetles don't like.

Fewer Beetles Through Chemistry

• Commercially available sprays can be used to control Japanese beetles. Sprays are best applied in June when adult beetle activity begins.
• Although traps are a popular option, they can actually attract more beetles than they repel if used incorrectly. Follow manufacturers directions carefully, making sure to place traps well away from plants you're trying to protect.
• Grub control powders and sprays are available from home and garden centers. Grub controls should be applied in July and august when young grubs are active near the surface.