Japanese Beetles

How to Get Rid of Japanese Beetles in the Garden

japanese-beetle-garden-pest-bug

Use these tips to get rid of Japanese beetles.

Crestock

Got iridescent green beetles feasting on your roses? Those would be Japanese beetles! Here are tips on how to identify and get rid of Japanese beetles.

What Are Japanese Beetles?

Japanese beetles (Popillia japonica) are small insects that carry a big threat. They do not discriminate when it comes to what types of plants they feed on, though they do have favorites (like roses). In fact, they are classified as a pest to hundreds of different species. They are one of the major insect pests in the Eastern and Midwestern United States, causing monumental damage to crops each year.

Prior to the beetle’s accidental introduction to the United States in the early 1900s, the Japanese beetle was found only on the islands of Japan, isolated by water and kept in check by its natural predators. In 1912, a law was passed that made it illegal to import plants rooted in soil. Unfortunately, the failure to implement the law immediately allowed the Japanese beetle to arrive in this country.

Most entomologists agree that the beetles entered the country as grubs in soil on Japanese iris roots. In 1916, these coppery-winged pests were first spotted in a nursery near Riverton, New Jersey, and by 1920, eradication programs were dropped; the beetle proved to be too prolific and widespread. 

Identification

How to Identify Japanese Beetles

Japanese Beetles are ½ inch in length with metallic blue-green heads, copper-colored backs, tan wings, and small white hairs lining each side of the abdomen. Japanese beetles usually feed in small groups. They lay eggs in the soil during June, which develop into tiny white grubs with brown heads and six legs that are up to ¾ inch in length. These grubs will remain underground for about 10 months, overwintering and growing in the soil.

They emerge from the soil as adult beetles and begin feeding the following June. They usually attack plants in groups, which is why damage is so severe. Although the lifecycle of the adult Japanese beetle is barely 40 days, it can cover a lot of ground. Even if you succeed in controlling your Japanese beetle population, your neighbor’s Japanese beetles might come on over.

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Photo Credit: Ohio State University. Japanese beetles cause leaves to appear skeletonized.

Signs of Japanese Beetle Damage

Japanese beetles feed on a wide variety of flowers and crops (the adult beetles attack more than 300 different kinds of plants), but in terms of garden plants, they are especially common on roses, as well as beans, grapes, and raspberries. Here’s what to look out for:

Skeletonized Leaves and Flowers

Japanese beetles can devour most of the foliage on favored plants, as well as the flowers. Look for leaves that are “skeletonized” (i.e., only have veins remaining). This is a tell-tale sign of Japanese beetles. (Mexican Bean Beetles can also leave foliage skeletonized, though, so be sure to identify the beetle by their appearance as well.) Japanese beetles are not usually far from damaged leaves, so inspect the plant thoroughly. Also keep an eye on the ground beneath the plant; the beetles may reflexively drop off the plant if disturbed.

Unhealthy, Brown Patches in Lawn

Japanese beetle grubs damage grass when overwintering in the soil, as they feast on the roots of lawn grasses and garden plants. This can cause brown patches of dead or dying grass to form in the lawn, which will pull up easily thanks to the weakened roots. 

Control and Prevention

How to Get Rid of Japanese Beetles

Good horticultural practices, including watering and fertilizing, will reduce the impact of the damage caused by these beetles, but oftentimes you simply need to get rid of them. Here are some ideas:

  • Row Covers: Protect your plants from Japanese beetles with row covers during the 6- to 8-week feeding period that begins in mid- to late May in the southern U.S. and in mid- to late June in the North. Row covers will keep the pests out, but they will keep pollinators out, too; be sure to remove them if your crops need to be pollinated.
  • Hand Pick: Unfortunately, the most effective way of getting rid of Japanese beetles is to hand pick them off of plants. It’s time consuming, but it works, especially if you are diligent. When you pick them off, put them in a solution of 1 tablespoon of liquid dishwashing detergent and water, which will cause them to drown.
  • Neem Oil: Neem oil and sprays containing potassium bicarbonate are somewhat effective, especially on roses. The adult beetles ingest a chemical in the neem oil and pass it on in their eggs, and the resulting larvae die before they become adults. Note: Neem can be harmful to fish and other aquatic life, so don’t use it near lakes, rivers, and ponds. It must be reapplied after rain.
  • Use a Dropcloth: Put down a dropcloth and, in the early morning when the beetles are most active, shake them off and dump them into a bucket of soapy water.
  • Insecticides: If you wish to spray or dust with insecticides, speak to your local cooperative extension or garden center about approved insecticides in your area.
    • Or, try this homemade solution: Mix 1 teaspoon of liquid dishwashing detergent with 1 cup of vegetable oil and shake well; then add it to 1 quart of water. Add 1 cup of rubbing alcohol and shake vigorously to emulsify. Pour this mixture into a spray bottle and use it at ten-day intervals on pests.
      Warning: Homemade sprays can run more of a risk of damaging plant leaves, so be careful and use sparingly. It’s always a good idea to first test a little bit of your spray on a small part of your plant, wait 24 hours to see if there are any adverse reactions, and—if not—proceed with spraying the rest of the plant.
    • Apply sprays in the morning, never in full sun or at temperatures above 90ºF. If your plants start to wilt, rinse the leaves immediately with clean water.
  • Japanese Beetle Traps: Japanese beetle traps can be helpful in controlling large numbers of beetles, but they also might attract beetles from beyond your yard. Eugenol and geraniol, aromatic chemicals extracted from plants, are attractive to adult Japanese beetles as well as to other insects. Unfortunately, the traps do not effectively suppress adults and might even result in a higher localized population. If you want to try them, be sure to place traps far away from target plants so that the beetles do not land on your favored flowers and crops on their way to the traps.
    • Fruit Cocktail Trap: You can buy Japanese beetle traps of all sorts, but most are no more effective than a can of fruit cocktail. Open the can and let it sit in the sun for a week to ferment. Then place it on top of bricks or wood blocks in a light-colored pail, and fill the pail with water to just below the top of the can. Place the pail about 25 feet from the plants you want to protect. The beetles will head for the sweet bait, fall into the water, and drown. If rain dilutes the bait, start over. 
  • Geraniums: Japanese beetles are attracted to geraniums. They eat the blossoms, promptly get dizzy from the natural chemicals in the geranium, fall off the plant, and permit you to dispose of them conveniently with a dustpan and brush. Plant geraniums close to more valuable plants which you wish to save from the ravages of Japanese beetles. 
  • Japanese Beetles on Roses? Note that insecticides will not fully protect roses, which unfold too fast and are especially attractive to beetles. When beetles are most abundant on roses, nip the buds and spray the bushes to protect the leaves. When the beetles become scarce, let the bushes bloom again. Timeliness and thoroughness of application are very important. Begin treatment as soon as beetles appear, before damage is done. 

For rose growers, see our Growing Guide for Roses for more tips on caring for roses!

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Photo Credit: Jeff Hahn, University of Minnesota. Sometimes the easiest way to get rid of Japanese beetles is to pick them off the plants before they do too much damage.

How to Prevent Japanese Beetles

Unfortunately, there is no magic potion to get rid of this pest. For general preventive maintenance, experts recommend keeping your landscape healthy. Remove diseased and poorly nourished trees as well as any prematurely ripening or diseased fruits, which can attract Japanese beetles. Try these tips:

  • Choose the Right Plants: Select plants that Japanese beetles will not be attracted to. See our list of the Best and Worst Plants for Japanese Beetles. Dispersing their favorite plants throughout the landscape, rather than grouping them together, can also help.
  • 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.
  • Milky Spore: You can introduce the fungal disease milky spore into your lawn to control the Japanese beetle larvae population. The grubs ingest the spores as they feed in the soil. The spore count must be up for two to three years for this method to be effective. Fortunately, the spores remain viable in the soil for years. This is an expensive treatment, as all the soil within five-eights of a mile needs to be treated for good control.
  • Beneficial Nematodes: You can also drench sod with parasitic nematodes to control the larvae. The nematodes must be applied when the grubs are small and if the lawn is irrigated before and after application. Preparations containing the Heterorhabditis species seem to be most effective.
  • Plant Strategically: Companion planting can be a useful strategy in preventing pests. Try planting garlic, rue, or tansy near your affected plants to deter Japanese beetles. 
  • Parasitic Wasps: You can also attract native species of parasitic wasps (Tiphia vernalis or T. popilliavora) and flies to your garden, as they are predators of the beetles and can be beneficial insects. They will probably attack the larvae, but they are not very effective in reducing the overall beetle population. 

WARNING: Many dusts or sprays are highly toxic to honeybees, native bees, and other pollinators. If application of these materials to plants is necessary during the bloom period, do not apply during hours when bees are visiting the flowers (late morning through mid-day). If more than just a few yard and garden plantings are to be treated, you may need to contact nearby beekeepers in advance so that they can protect their colonies. 

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Reader Comments

Leave a Comment

Bull! There is either more to

Bull!

There is either more to the story you are not telling us or you just pulled the whole thing out of your imagination.

Japanese beetles/ malathion

Why did the lady get prosecuted and fined? Was it the malathion or is it because you are not supposed to kill those beetles?

Malathion/EPA

Your reply is false. The EPA has approved the use of this product since 1956.
Visit the EPA's website so you can read all about it.

I have perennial hibiscus and

I have perennial hibiscus and Japanese beetles are eating them up! What can I use on them to get rid of the beetles.

The Japanese Beetle does love

The Editors's picture

The Japanese Beetle does love hibiscus. You need to put on some gloves and-pick the beetles in the early morning when they are sluggish and drop into a can filled with soapy water. The presence of beetles attracts more beetles.  You could use Reemay or other spun-bonded material to protect your plant for a while. Unfortunately, many organic sprays don't work and most of the chemical applications have high toxicity to bees which pollinate your plants. If all fails, consider choosing plants they do not like such as poppies, hosta and coreopsis. See more advice on this page.

The bettles I have in my yard

The bettles I have in my yard and garden are not green. They are closer to shinny brown/orange and start feeding at 10:00 pm sharp. They live right in the ball of the plants down in the soil. The only solution I know is to dig them up during the day and hand-kill them. I have manually killed about 500 in one day, easily. So which other Japanese beetle is the green ones?

We can try to help. Please

The Editors's picture

We can try to help. Please tell us where you live? Which vegetables or plants are the beetles eating? What type of holes/evidence do they leave?

I would like a list of the

I would like a list of the plants the J Beatles feed on:

Here are the ones I have noticed in my garden:

Hibiscus blooms
Connester's leaves [evergreen]
Maple Trees
Roses [a given]
Petunias blooms
Wisteria leaves
Milk Weed "
Purple Plum Bush "
Burning Bush "

Adult Japanese beetles feed

The Editors's picture

Adult Japanese beetles feed on nearly 300 different host plants. Yes, roses are the ultimate feast. Other favorites include: flowering cherry and crabapple, zinnias, canna, marigolds, crape myrtle, linden, Japanese maple, and birch. Here is a helpful reference page of plants that are commonly damaged and plants that are seldom damaged:
http://www2.ca.uky.edu/entomol...

I have green beetles and they

I have green beetles and they have destroyed my Cherry tree Grape Myrtle , roses all over our yard , They are sexing in large groups now like Sodom and Gomorrah so now I guess I need to soap my yard all over for several weeks now. These are Madding insects.

What Japanese beatles feed on

I have also noticed they really love my ferns!!! Also they always seem to come out around the 4th of July

Is it o.k. to use the remedy

Is it o.k. to use the remedy of two tablespoons of dishsoap in a gallon of water around fruit trees and blueberry bushes. I did not know if it would do anything to the trees.

Hi Keith, The dishsoap mixed

The Editors's picture

Hi Keith,
The dishsoap mixed into a gallon of water is not going to harm your bushes or trees.

Is there something that can

Is there something that can be added in the spring when tillilng soil that will help control the grubs that turn into the Beatle

Hi Timothy,   Milky spore

The Editors's picture

Hi Timothy,
 

Milky spore powder and beneficial nematodes are a natural way of getting rid of grubs in the soil. Check your local garden center or do a quick search online to find out more about how to use them.

What about fruit and

What about fruit and vegetables in gardens? will this mixture help them or hurt them? I remember my dad used to use mixture to spray the lawn. I don't remember why. to kill bugs? thanks!!

This year my peony brushes

This year my peony brushes grew usually long stems, them many of them twisted and curled around. On those stems the blossom grew but turned brown and of course never blossomed.

Do you have any ideas?

I was told to get rid of

I was told to get rid of Japanese Beetles to spray your plants with a mix of 2 tbls of vanilla extract and water.
They are on my rosé bushes and just showed up in the last 2 days.
Is this been tried by anyone?

We haven't heard this.

The Editors's picture

We haven't heard this. However, you want want to cover your roses with cheesecloth or a fine netting during the peak of beetle activity.
If you find that natural solutions don't work, repeated chemical applications (malathion or sevin) are really the best control against Japanese beetles.

I saw a video where the

I saw a video where the beetle ate a slug, so they aren't all bad.

you might change your mind

you might change your mind when you find all of your beautiful formerly healthy plants dying and stripped of leaves. Like mine. :(

japanese beetle control

I've read article and most of the comments. I've been battling these horrible beetles for 4 years not. I used the bags first then bought one of the tangle foot traps with a jar that screws off. the task of emptying the jar and the bags every 10 minutes was too much so I took my sawsall and cut the bottom off the screw on jar. then I used that bottom as the measurement for the lid of a old 5 gal. oil bucket. I cut the hole then slide the jar in about 3/4 of the way then put foam like you seal windows with around the jar to hold it in place. it worked like a charm!! I baited the trap with the lure that came with the trap and about 2 hours later when I checked the trap was almost full! I had made sure the little tabs that hold the lid on the bucket were already loose so it was easy to get the lid off to empty the bucket. one word of caution. do not put the beetles in your garbage can or dumpster or anywhere near your house!! dead beetles smell horrendous! this worked so well I made 4 more buckets. the tangle foot traps are kind of expensive. about 30.00. but if you have a the thousands upon thousands of beetles like I do they are well worth the money. the farmers around us spray their fields. I don't want to kill every bug that comes into my little farm. traps have worked well for me.

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