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Adult Japanese beetles feeding on foliage. Photo credit: Bonnie Plants

 How to Get Rid of Japanese Beetles

Japanese beetles appear in the summer and chew tell-tale holes in your precious plants and produce. Most gardeners disdain Japanese beetles for their attacks on ornamental plants. However, the beetles will also damage vegetables like corn, asparagus, and rhubarb. And while they may appear in large numbers, you don’t have to sit back and watch your garden become a snack. Here’s how to prevent and control Japanese beetles.

What are Japanese beetles?

Japanese beetles are a widespread, invasive pest that feeds on everything from turfgrass to ornamentals to vegetables. In fact, they’re known to eat over 300 species of plants. So, for a wide portion of the United States,  there’s a solid chance that if you have plants, you also have Japanese beetles.

What does Japanese beetle damage look like?

Japanese beetles eat the foliage off plants. You may see a few chewed pieces, or the damage may be so severe that only the veins of the leaf remain (also referred to as skeletonizing). The good news is, Japanese beetle damage is easy to identify, as these pests aren’t very good at hiding. You’ll also likely see the bugs themselves—they have shiny, metallic, brown and emerald-green bodies and are about 0.25” long.

What is the life cycle of Japanese beetles?

The life of Japanese beetles is complex. In the ground they are white grubs, best known for eating the roots of lawn grasses. They also attack the roots of corn (which is, technically, a type of grass). 

When adult beetles emerge from the ground in late spring and summer, they begin feeding on their favorite leaves and flowers. Fortunately, “beetle season” passes in summer as the adults die of old age. However, a new generation of grubs is feeding in the grass or elsewhere underground, preparing to return next year. 

What do I do about a Japanese beetle infestation?

First of all, recognize that Japanese beetles are virtually impossible to prevent. They’re so prevalent and eat so many different kinds of plant that if they live in your climate, you’re likely to deal with them at some point. However, there are a few things you can do to help minimize Japanese beetle damage.

  • Apply a pesticide dust that remains on the plant, such as Ortho® Insect Killer Flower & Vegetable Garden Dust
  • Apply a biological control (such as parasitic nematodes or Bt) to the lawn to help reduce the population next year. Sometimes neighbors get together to treat whole neighborhoods because the beetles can fly such long distances. 
  • Manually remove them. Don garden gloves, pluck them from your plants, and toss them into a bucket of soapy water. It’s not glamorous work, but it gets the job done.
  • Use a Japanese beetle trap. This consists of a bag or container with a yellow top that contains a scented disc that lures beetles inside—and keeps them there. Just be sure to place it away from the plants they’re currently eating, so you don’t draw more Japanese beetles to your precious produce.
  • Get local info. For more information about an integrated pest management approach to controlling Japanese beetles, contact your local county Extension office. You can find the nearest Extension office through the Cooperative Extension System map. A Google search for Japanese beetles in your state will also bring up plenty of information about control techniques recommended for your area.

Japanese beetles are an unfortunate reality for many home gardeners. However, that doesn’t mean they have to ruin your harvest. Follow one (or more!) of the suggestions above to remove these pesky invaders from your corn, asparagus, rhubarb, and more.

An adult Japanese beetle has a metallic brown and emerald-green body about 0.25” long. Photo credit: Bonnie Plants
Japanese beetle damage may be so severe that only the veins of the leaf remain. Photo credit: Bonnie Plants

Watch the video below for a quick guide to dealing with Japanese beetles in the garden.

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