Controlling Japanese Beetles

Many gardeners in our area have started seeing damage from Japanese Beetles. While these pests should be gone by the end of August, here are a few things you can do in the meantime to protect your plants.

Five Ways to Control Japanese Beetles

Play Defense: A multi-part attack is best. Start by spraying the affected plants with Japanese Beetle Killer (pyrethrin) or neem at the first sign of attack.

Japanese Beetle
Japanese Beetles

A pyrethrin-based insecticide is a safe and effective way to control these pests on vegetables, grapes, raspberries, flowers, roses, trees, and shrubs. In addition to controlling Japanese beetles, it controls cucumber beetles, flea beetles, cabbage worms, Colorado potato beetles, and more. 

Neem oil comes from a tree; spraying on plants reduces feeding. Scientists call it an antifeedant. Important: neem works best when applications begin at the first sign of attack.

Hand Pick: Japanese beetles are slow. You can easily pick them off plants with your hands and toss them into a bucket of soapy water. Do it in the morning when the beetles are less alert.

Prevent: Although the following solutions won’t provide immediate gratification, you will be better off next year. Grub Guard kills the grubs that turn into Japanese beetles. Ideally, apply it in spring before the beetles emerge.

The second half of this 1-2 prevention punch is Milky Spore, which also kills grubs. It takes a year or so to get established in your soil, but it keeps working for 10 years or more.

Trap: A Japanese beetle trap is recommended only if you have a large yard, and can place the trap away from your garden. If you have a small yard, you’ll just be telling the beetles, “The party’s at my house!” If you use a trap, put it out for a day or two at a time every couple of weeks. 

More information is available at “How to Control Japanese Beetles” by David Grist at Gardener’s

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