Japanese Beetles: Controlling Their Damage

08-09-2022_Japanese beetles

Japanese beetles (popillia japonica) have spread throughout most of the United States. These leaf, flower, and root munchers can harm your plants, gardens, and grass. While eradicating them entirely isn’t possible, there are some steps you can take to reduce their effects.

Identifying Japanese Beetles

japanese beetle on leaf

Japanese beetles are pretty easy to identify. They’re an iridescent green and copper color with long spindly legs. They can fly, and they tend to be clumsy flyers. Fortunately, they don’t bite or sting.

Though Japanese beetles aren’t picky eaters, they do have plants they prefer. If you have any of the following plants, keep an eye out for Japanese beetles, as adults feed on the following.

  • Apple, peach, and cherry trees
  • Grape vines
  • Raspberries and blackberries
  • Beans
  • Roses

Signs That You Have Japanese Beetles

Japanese beetles don’t dine in secret. If you have them, you’ll likely see them in clumps, munching and mating on your plant leaves.

The best time to search for Japanese beetles is early in the morning or later in the evening. However, Japanese beetles are ruthless, so don’t be surprised to see them at high noon.

Another sign that you have Japanese beetles is the skeletonization of leaves. Japanese beetles like to eat the delicate, fleshier parts of plants. Often, they’ll eat leaves around the veins, leaving just the outline of the leaf.

They also like the flowers of roses, beans, and grapes.

3 Ways to Control Japanese Beetles (How to Kill Japanese Beetles)

Eradicating Japanese beetles is a fool’s errand. However, you CAN control infestations. The best way to do so is to kill them as soon as you see them (and sometimes, before you can see them!) using one of the following three methods.

It’s important to note that insecticides rarely work to control adult beetles (and you certainly don’t want to use insecticides on any food you might eat).

soapy bath with dead Japanese beetles

1. Drown them in soapy water

The most effective way to control Japanese beetles is to scrape them off leaves and into a bath of soapy water. The soap prevents them from spreading their wings and flying away. After a while, they’ll drown.

Having a bath full of dead Japanese beetles doesn’t attract more beetles and may even deter others from coming to the area.

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2. Crush them

If you don’t have soapy water handy, just crush them. This is a little more challenging because the beetles will fly away if you don’t get them quickly enough. We recommend wearing gloves if you choose this method.

Japanese beetle grub

Picture source

3. Treat your lawn with grub killer in late summer

Japanese beetle grubs begin their life cycle in your lawn and can destroy patches of your grass. If you notice that your lawn is suddenly browning and pulls up like carpet, you likely have grubs.

A good way to mitigate the effect of grubs (and reduce local adult numbers) is to apply a grub killer in late summer—between the beginning of August and the middle of September.

There are several kinds of grub killers you can purchase at your local hardware store. Be sure to read any instructions about applying, watering in, and any harm it can do to pets or other wildlife.

For example, Dylox is a powerful weapon against grubs. However, it’s also toxic to humans, fish, birds, and other wildlife. When using such insecticides, you must take caution and follow all instructions closely.

Should You Use Japanese Beetle Traps?


Japanese beetle traps use the same pheromones to attract beetles that the beetles themselves use. So, if you have a lot of beetles, the traps will just attract more, and the traps rarely kill more than they attract.

Likewise, if you only see a few beetles at a time, a trap will give more beetles a target to aim at.

Though it may be tedious, your best bet is to kill them by hand.


Conclusion: Control is the Best Option

Japanese beetles are a fact of life for homeowners who want a lush lawn or gorgeous garden. The best way to control Japanese beetles is to kill them by hand, either in a soap bath or by crushing them. And taking steps to kill the grubs is another way to reduce their numbers.

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