Japanese Beetles

How to Identify and Get Rid of Japanese Beetles

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Use these tips to get rid of Japanese beetles.

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What are those green garden beetles? Here are tips on how to identify and get rid of Japanese beetles.

What are Japanese Beetles?

Japanese beetles are small bugs that carry a big threat. They do not discriminate on what types of plants they feed on. 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 into 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 enemies. 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. By 1920, eradication programs were dropped; the beetle proved to be too prolific a breeder. Not a choosy eater, it dines on over 200 species of plants.

Identification

How to Identify Japanese Beetles

Japanese Beetles are ½ inch in length with metallic blue-green heads, copper 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 under wraps for about 10 months, overwintering and growing in the soil.

They emerge from the soil as adult beetles and begin feeding in 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.

Japanese Beetle Damage

Japanese beetles eat a wide variety of flowers and crops (the adult beetles attack more than 300 different kinds of plants), but they are especially common on roses, as well as beans, grapes, and raspberries.

They can devour most of the foliage on favored plants like roses. Look for leaves that are “skeletonized” (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 them by their appearance as well.

Grubs damage grass when overwintering in the soil, as they eat the roots of lawn grasses and garden plants.

japanese-beetle-damage.jpg
Photo Credit: The Ohio State University. Japanese beetles cause leaves to appear skeletonized.

Control and Prevention

How to Get Rid of Japanese Beetles

Good horticultural practices, including watering and fertilizing, will reduce 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.
  • Hand Pick: Unfortunately, the most effective way of getting rid of Japanese beetles is to hand pick them. 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 adults ingest a chemical in the neem oil and pass it on in their eggs, and the resulting larvae die before they become adults. Neem can be harmful to fish and should be reapplied after rainstorms.
  • Use a Dropcloth: Put down a dropcloth and, in the early morning when they’re 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 safe 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. Homemade sprays can run more of a risk of damaging plant leaves, so be careful.
    • 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.
  • 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 plants so that the beetles do not land on your favored plants on their way to the traps.
  • Fruit Cocktail: 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, fall down, 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 free Roses Guide for more tips on caring for roses!

japanese-beetle-identification-control.jpg
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:

  • 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.
  • 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.
  • You can introduce the fungal disease milky spore into your lawn to control the Japanese beetle larvae population. The larvae 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.
  • 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.
  • Companion planting can be a useful strategy in preventing pests. Try planting garlic, rue, or tansy near your affected plants to deter Japanese beetles. 
  • 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. 

NOTE: Many dusts or sprays are highly toxic to honeybees. If application of these materials to plants is necessary during the bloom period, do not apply during hours when bees are visiting the flowers. If larger than yard and garden plantings are to be treated, you may need to contact nearby beekeepers in advance so that they can protect their colonies. 

Plants Affected

Reader Comments

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Another trick on the beetles

I put just a little bleach in a bucket of water and floated one of the beetle bait lures on top of the water. I put the bucket on the ground under a trap. It is catching them! When the top is covered, I take a flower pot with holes in the bottom and scoop them out, let the water drain, then put them in a plastic bag. Good bye beetles.

Beetle Traps

I just hung a beetle trap yesterday at 10:30 in the morning. I had one bag full in 2 hours. Two hours later, another bag full and 2 hours after that another bag full and one more bag after that so in 8 hours, I had 4 bags full. I put a bucket of the fermented water mixture under the trap and some got in it but overnight, a raccoon turned the bucket over. I will see how many I get today.

Beetles by the bagful!

Oh, my! It sounds like the air is thick with swarms of beetles, Marty! Is this normal where you are??

Beetle traps

I first saw them about 3 years ago. There was a soybean field across the road from me so that may be what brought more in. I was really shocked to see that many! I was trying to get them off my elderberry bush. I did hear there was a couple down the road that has a Mimosa tree that is covered with them. This morning I have already filled two more bags. I am curious to see when they will slow down. I guess the more I get rid of this year the less there will be next year.

Beetles

I have been getting two filled bags a day for past two weeks. Can not imagine where they all are coming from. Only had them past 3 years. My question is what can I do twitch them , they stink so bad I can’t put in my trash cans and I feel bad for the trash men. Any ideas??

japanese beetle traps

Can you send pics and info on how to make your traps that work thanks

Japanese Beetle Traps

I purchased the Japanese Beetle trap. It comes in a box with 2 bags and the bait lure. It has directions for putting it together and you hang the bag on the hooks at the bottom. I also purchased a bait lure separately that I float in the bucket.

I went to Sutherland's and

I went to Sutherland's and bought a Japanese/Oriental Beetle trap and the results were amazing! In about 12 hours the bag was full. I wish I had bought more.

What to do when the beetle bag is full

Try the fruit cocktail trick (noted above and repeated here, for expediency): Get a can of fruit cocktail at the grocery store. 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. 

When beetle bag is full

Since I had so many, I laid the bag in the sun to let the beetles die then I empty that bag into a ziploc bag and zip them up and I can reuse my trap bag over and over.

Japanese Beetles take over central Iowa

I noticed hundreds of these bugs all over a large tree (I don't know what kind of tree) and it was practically devoured by the bugs. They moved on to another tree just like it. I found this website and made the natural mixture. soap, oil, water and alcohol. I sprayed the trees at sundown. I couldn't tell if there were any beetles on the trees or not since it was getting too dark. Do they hide at night?
I will let you know tomorrow if it did the trick
Thanks for the information.

Iowa girl

are beetles active at night?

Research suggests that the beetles are most active on warm, sunny days between the hours of 9 AM and 3 PM but they also may feed at night.

Japanese beetles like amaranth plants

Japanese beetles seems to enjoy eating my amaranth plants. So we can add amaranth to the list. (Amaranth is known to farmers as pig weed.)

JB

Has anyone found peppermint oil an effective deterrent?

peppermint oil

Back in 2009, a study was published that had looked into how well various essential oils helped to repel Japanese beetles. Wintergreen was the best, followed by peppermint oil; a combination of the two were even more effective. These weren’t foolproof (some years yielded better results than others), but they were better than other essential oils at repelling Japanese beetles from traps baited with an attractant.

these bugs are really stupid

for some reason my room is filled with those bugs and i can't get rid of them

Better than hand picking

I use a shop vac to vacuum up Japanese beetles off my plants. Adding pieces of PVC pipe as an extension to the tubing lets you reach up high. Try different sizes of vacuum attachments to get suction enough to grab beetles with little damage to the plant. It's very emotionally satisfying to pour bleach on several gallons of beetles at one time, die beetles!! :) Wonder how many beetles are in a gallon?

And if you do the tarp trick mentioned in the article, do it when it's chilly before dawn, as soon as they warm up they will start flying. Sweep them off the tarp and into a can often, so if it warms up a degree or so and they start flying, they don't get away.

Hoover for J.B.

Thank you for your trick on the J.B. ; hoovering them into eternity seems to do the trick when you 've got the luck :s or rather mishap to have sacks full of these destroyers .
May I suggest to , rather than putting them into realy nasty bleach , put them in a paper bag , place it in front of your car tyre and crush them out loud :op
U can also do it with your foot or sth. similar .
Good luck !

Japanese Beetle solution

I have elderberries that Japanese Beetles seem to really relish. Insecticidal Soap did a fair performance controlling them. However they would come back fairly soon and even before the next rain. Neem Oil did a much better and longer control on them. They stayed away until the next very hard rain which is not exactly common in my part of Arkansas in the deepest throes of summer. Like the article says hand picking (Which I do) is great method, however, when you have 50 elderberry plants that can get pretty tedious. I was literally picking quarts of them a day before using Neem oil. Filling a five gallon bucket a week. In my 50+ years, my particular site here in North Central Arkansas had never seen them until three years ago.

Neem oil

Thanks so much for your suggestion of the Neem oil. I just discovered the beetles for the first time ever today. They were enjoying my large pots of Hibiscus, my most treasured flowers! Then I saw them on my Knockout rose bush devouring one bloom. A minimum of 6 were chewing away, crawling over one another. I have a spray bottle of Neem, went right out and sprayed the heck out of the Hibiscus and rose bush, and I am now Japanese beetle free!!

shop vac

I have considered using a shop vacuum but was afraid that it might make the vacuum stink, what's your experience?

For trees I use Bayer

For trees I use Bayer Advanced 12 Month Tree and Shrub Protect and Feed Concentrate works great but you need to put it on by the beginning of May. For roses I use Bayer Advanced Rose & Flower Care Plant Food For Shrubs Ornamentals every 6 weeks. Works very well. I need something for my raspberries. This year I am covering them with tomato cages and netting. I hope that works.

Raspberry bushes are roses

Raspberry bushes are in the rose family. The same treatment as the roses should work with them.

Beetle Battle

Ivctried everything against the beetles. I mean everything. There is not a plant or tree or shrub in my yard that they do not love. It's so discouraging to find them attacking everything all day as soon as my flowers start to mature. No one mentioned it, so I will. I used the buckets of soapy water for years. Now I find it easier, faster and more effective to just slip on the gardening gloves and and starting to smash them. I pull them off and crush them and drop them. Usually, I can pick 4 or 5 at a time. I know they are dead, and I don't have to use any tools or water or soap or powder or anything. Just grab them and crush them. I'm so sick of these things I use my bare hands when my gloves aren't with me.

Milky Spore

Use Milky spore. It's the only permanent solution! It works..but it might take two or three times.

Do not crush Japanese beetles

Do not crush them. I did some research and found that they release pheromones when you crush them which attracts even more beetles. I run around my yard a few times a day with a jar of soapy water. Works for me.

Japanese Beetles

I usually just crush them between my fingers. But yesterday they were out of control. So now don't know what to do!! Someone please help me

Where do I get milky spore?

Where do I get milky spore?

japenese bettles

where can i get milky spores?

Where to get milky spores

If you are near an ACE Hardware store, check there. Otherwise check Amazon they also have Milky Spores. Nematodes seem to be a nice natural way to combat Japanese Beetles. Easy to apply if you follow the directions for spraying. Remember to remove all filters from your sprayer so the Nematodes get out. Follow directions for time of day. You can tell if your efforts are effective, the skunks and raccoons will stop digging up your lawn to get at the grubs for food.

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