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How to Prevent Japanese Beetles

July 8, 2022



Japanese Beetles feed on the leaves, fruit, and flowers of hundreds of plant species. Their damage is easy to identify.  Since they feed primarily on the soft tissue parts of the leaves you will see leaves that look like ‘skeletons’, meaning only the veins of the leaves are left. 

You can prevent adult Japanese beetles by exterminating the larvae, or grubs before they ever have a chance to mature. 

Japanese Beetle Prevention

grub Control

When to treat grubs: Grubs are active in the lawn in early spring and early fall. 

Get Rid of Grubs: In the grub stage of late spring and fall (beetles have two life cycles per season), spray the lawn with 2 tablespoons of liquid dishwashing soap diluted in 1 gallon of water per 1,000 square feet. The grubs will surface and the birds will love you. Spray once each week until no more grubs surface.

Or use these methods to get rid of grubs before they become Japanese beetles:

Neem oil 
Lawn-aerating sandals
Beneficial nematodes
Milky spore
Attracting birds

5 Natural Control Methods

If you want to avoid chemical insecticides (which we highly recommend), here are some organic methods you can try first. 

The best time to try these methods is August through September, when newly hatched grubs are actively feeding on grass roots. 

Beneficial nematodes are microscopic, living creatures that feed on grubs. Nematodes are a long-term solution because they reproduce on their own and continue feeding on grubs (and other pests) for years. 

Because nematodes are alive, you have to introduce them to the lawn soon after you purchase them. They love moisture, so water the lawn before and after application, unless the ground is already wet from rain. 

Milky spore is a bacterium that infects Japanese beetle grubs. It’s one of the oldest and most popular natural solutions to Japanese beetle grubs, but it requires patience. After you release the bacterium into your soil, it can take up to three years to work. 

When you purchase milky spore, it comes as a powder. To apply, add a teaspoon of the powder to every 4 feet of your lawn. Water the lawn after applying. For best results, add milky spore to the lawn when the soil is between 60 and 70 degrees Fahrenheit. 

Note: Milky spore doesn’t work on all grubs, only Japanese beetles. Distinguishing between different species of grubs is extremely difficult. Only use milky spore if you’ve had Japanese beetles before and you’re certain that’s the kind in your lawn now.

Neem Oil:

There are two types of neem oil: raw neem oil that contains the insecticide azadirachtin and clarified hydrophobic neem oil, which has most of the azadirachtin removed. 

Clarified hydrophobic neem oil is usually the kind you’ll find in stores. You can use clarified hydrophobic neem oil to suffocate grubs in your soil. 

Purchase a neem oil spray or mix one yourself with this recipe:

Step 1: Mix ⅓ teaspoon of mild or natural soap (like Castile soap) into 1 quart of warm water. 
Step 2: Shake well. 
Step 3: Add 1 teaspoon neem oil to the mixture and shake well again. 
Spray it on and around the brown patches in your lawn to suffocate grubs. 

Warning: Neem oil can damage plants, so be careful not to get any on your garden plants. Grass is hardier and usually won’t suffer damage. Neem oil can harm beneficial insects, as well.

Lawn-aerating sandals 
Yes, believe it or not, we mean the sandals that go on your feet. Lawn-aerating sandals are sandals with spikes on the bottom. They’re meant to poke holes in the soil for lawn aeration, but you can use them for grub control. 

This method is quite simple. Wear the sandals and walk across your lawn a few times, concentrating on areas with brown patches. When the spikes poke into the soil, they should stab through at least some of the grubs in your lawn. 

The sandal method may not solve large infestations. But if you have a small number of grubs in your lawn, aerating sandals could be worth a try. 

Attract Birds:

Many birds feed on grubs (and adult beetles, too). A grub infestation alone is often enough to attract birds, but you can attract even more if you set up birdhouses, feeders, and baths around your yard. 

The more birds you have hanging around, the more they’ll decimate your lawn’s grub population. Plus, a large number of predators can deter more adult beetles from moving into your lawn and laying eggs in the future. 

Hand-picking and drowning the beetles in soapy water is an option if their population is low.

As a last resort, spot treat adults with botanical pesticides. Apply to all leaf surfaces and deep into the plant canopy where insects hide.

Japanese Beetle Prevention
Beetle Trap

Beetle Trap

Once the beetles are present in your yard, you can trap them in a bag. For traps to work, they need to be in a designated area of your yard, 30 feet away from plants or garden areas where beetles normally feed.

If the trap is placed close to a rose bush, for example, the beetle will at first be attracted to the area because of the trap, but once it arrives it will choose the rose bush. If the trap is 30 feet away, however, the beetle goes to the trap and has no other options for feeding.

How It Works:

The trap uses floral scents proven to be a natural attractant, along with the beetle’s natural sex attractant. The trap uses a scientifically designed method to control the release of these natural floral and sex attractants to lure both male and female beetles to the trap. The convenient plastic cone design prevents the user from having to handle the actual attractants.

Purchase our  Japanese Beetle Traps online for in-store or curbside pickup. 

One Last Tip:

Stop watering your lawn.

Japanese beetles will lay eggs in your soil, and those eggs need moisture to survive. The fewer eggs that survive, the fewer adult beetles you’ll have in your garden later.

So, you want your lawn to be as dry as possible during the beetles’ egg-laying season, which is usually June through August. During that time, stop watering your lawn and let it go dormant so the eggs die instead of hatching. 

Disclaimer: A dormant lawn isn’t exactly pretty. Your grass will eventually start to yellow if you stop watering it, but if it’s healthy, it should spring back to life when you resume watering. One summer without a green lawn could be worth ending the cycle of grubs and Japanese beetles.

Japanese beetle