The Japanese beetle is a highly destructive plant pest that creates havoc for lawns, golf courses, and agricultural plants. Originally native to the Japanese archipelago, this shiny, metallic-green insect arrived in the United States in the early 20th century and has since become a major nuisance for gardeners and farmers alike.
Feeding on more than 300 different types of plants, the Japanese beetle attacks foliage, flowers, and fruit, causing significant damage and sometimes even destroying entire crops. Homeowners and landscapers must be vigilant in detecting and controlling these pests to prevent costly consequences.
Part of the challenge in controlling a Japanese beetle infestation is recognizing their various life stages. Adult beetles feature bronze-colored outer wings and distinctive tufts of white hair along their body. Knowing how to identify and manage each stage of the beetle’s life cycle can help curb their damaging presence.
Japanese Beetle Overview
The Japanese beetle (Popillia japonica) is a striking insect, characterized by its bright metallic green head, thorax, and abdomen. Some other features include:
- Dark green legs
- Brown wing covers
- White tufts of hair along the sides and back of the body
- Males are smaller than females
The lifecycle of the Japanese beetle consists of four main stages:
- Eggs: Laid in the soil by adult females
- Larvae: C-shaped white grubs that feed on grass roots
- Pupae: Inactive stage, transforming from larvae to adults
- Adults: Active, feeding on foliage, flowers, and fruits
Here’s a brief comparison of larvae and adult beetles:
|C-shaped grub||Metallic green head, thorax, abdomen|
|Feed on grass roots||Feed on more than 300 different ornamental plants|
In conclusion, the Japanese beetle is a highly destructive pest with a distinct appearance and lifecycle, making it important to be able to identify and understand its behavior.
Distribution and Impact
United States Infestations
The Japanese beetle, an invasive insect native to Japan, was first introduced to the United States in New Jersey in 1916. Since then, it has spread widely throughout most of the eastern United States, reaching the Mississippi River, and some western states including Arkansas, Kansas, Minnesota, South Dakota, and Oregon.
- Eastern States: Widespread infestations
- Western States: Limited infestations
This beetle can cause significant damage to grass roots, resulting in harm to lawns, golf courses, and pastures. Additionally, Japanese beetles feed on the foliage, flowers, or fruits of more than 300 different ornamental and agricultural plants, impacting both landscape and crops.
Quarantine and Regulations
To prevent further spread and mitigate their impact, quarantine and regulations have been established:
- Oregon is currently implementing a Japanese beetle eradication project, targeting areas with lawns and ornamental planting beds.
- Treatment for Japanese beetles typically occurs from April to July, consisting of up to two treatments.
|Oregon||Eradication Project||April – July|
By following these measures, authorities aim to minimize the Japanese beetle’s impact on plants, crops, and overall ecosystem health.
Host Plants and Feeding Habits
Favored Plants for Feeding
Japanese beetles preferentially feed on a variety of plants. Some examples of their favored woody plants include:
- Mountain ash
For crops and other landscape plants, they target:
- Garden vegetables
Japanese beetles tend to avoid certain plants as well. One way to limit their impact is by selecting plants they usually avoid, such as wild weeds 1.
Feeding Damage Patterns
Japanese beetles damage plants in various stages of their lifecycle. The grubs harm grass roots, affecting lawns, golf courses, and pastures. They also attack host plants, including turf and yard plants (like turfgrass), as they seek moist soil to lay their eggs 1. Adult Japanese beetles feed on more than 300 different host plants, targeting their foliage, flowers, and fruits 2.
|Life Stage||Feeding Damage||Examples|
|Grubs||Damage grass roots, lawns, golf courses, pastures.||Lawns, golf courses, pastures.|
|Adults||Damage foliage, flowers, and fruits of host plants.||Roses, maples, beans, corn, vegetables|
Natural Predators and Parasites
There are several natural predators and parasites that can help control Japanese beetles, such as:
- Tachinid flies: These flies lay eggs on adult beetles, and the larva consumes the beetle from the inside.
- Spined soldier bugs: These insects prey on Japanese beetle grubs in the soil.
Including plants like marigolds and larkspur can also attract predatory insects.
Insecticides can be applied to lawns to control both larvae and adult beetles. Examples include:
- Imidacloprid: Targets larvae in the soil
- Carbaryl: Effective against adult beetles on plants
- Kills larvae and adult beetles effectively
- Protects plants from damage
- May harm non-target insects
- Requires regular applications
|Insecticide||Target Stage||Application Site|
Traps can be used to capture adult beetles, using pheromones and floral lures. Examples include:
- Japanese Beetle Trap: Attracts beetles, catches them in a disposable bag
- Reduces the adult beetle population
- No chemicals needed
- May attract more beetles to the area
- Doesn’t address larvae in the soil
Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.
Letter 1 – Japanese Beetle on Cannabis
Subject: Is this Japanese Beetle going to eat my medical marijuana?
Geographic location of the bug: Ohio
Time: 12:28 PM EDT
Your letter to the bugman: Dear Bugman,
The Japanese Beetles were terrible this year. They ate all the leaves off my neighbor’s ornamental plum tree. They decimated the roses, and at times they seem to want to eat everything in sight. They ate my friend’s hawthorn. I keep finding one or two when I inspect the medical marijuana I just started growing this year, but they don’t seem to be eating the plants. I have tried to research Japanese Beetles and marijuana and I was thrilled with your section on Insects and Cannabis called What’s on my Woody Plant?
So I expect my girls to start producing buds soon. Do I need to fear the Japanese Beetles eating my marijuana?
How you want your letter signed: Paranoid Pot Grower
Dear Paranoid Pot Grower,
Time may be on your side, especially since the Japanese Beetles you are finding do not appear to be eating the leaves on your plants. According to BugGuide: “Larvae feed on roots of many plants. adults feed on more than 350 different species of plants, but are especially fond of roses, grapes, smartweed, soybeans, corn silks, flowers of all kinds, and overripe fruit.” Your buds are flowers, so they might be attractive to the beetles if there is no other preferred food to be eaten. BugGuide also states Japanese Beetles are active “mostly: June-Sept” and we suspect your harvest will be after late September, so you shouldn’t have to worry about loosing your entire crop. According to Holy Moly Seeds, Japanese Beetles eat: “Mainly roses, grapes, cannabis, beans, strawberries, tomatoes, peppers, grapes, hops, cherries, plums, pears, peaches, berries, corn, peas, and many more. They feed on the foliage of the plant, eating the material in between veins.” According to Medical Marijuana (Cannabis sativa x indica): “Japanese beetles will eat the entire leaf. Just like home gardens a population of Japanese beetles can kill a whole plant by destroying its leaves so badly it cannot photosynthesize enough to support itself” but you do not seem to be experiencing that. Medical Marijuana Cannabis Pests says nothing about leaves and buds, but it does state: “The most serious root pests are flea beetle grubs (Psylliodes attenuata) and white root grubs — Japanese beetles (Popillia japonica) and chafers (Melolontha hippocastani and M. melolontha).” Please give us an update if you do find the Japanese Beetles are eating your buds.
Letter 2 – Buckets and buckets of Japanese Beetles collected in Ohio
Subject: Invasion of the Japanese Beetles
Geographic location of the bug: Campbell, Ohio
Time: 07:11 AM EDT
Those of you who are new to this site don’t know that there was a period of time when Daniel would respond to 20 or more identification requests per day. Now Daniel does all he can to avoid working on the computer, preferring instead to work in his gardens. Right now he is working in his inherited homestead in Eastern Ohio where large lawns with no trees or shrubs or flowers are popular with much of the population. Lawns are the breeding grounds for the grubs of the dreaded, invasive Japanese Beetles, which were accidentally introduced to the eastern states in 1917 with imported horticultural specimens. Gardeners’ preferences for exotic plants over native plants will likely never be fully altered, but that matters not with Japanese beetles that feed on over 300 species of plants, many of them native. They have proliferated without any natural enemies and daily, now that it is Beetle Season, Daniel picks beetles by the bucket.
Daniel puts about an inch of water in a plastic bucket and adds a squirt of dish soap. To that he adds a few drops of motor oil. It is best to collect Japanese Beetles early in the morning or at dusk because they are most active and more likely to take flight when disturbed if it is sunny. When they are less active, they tend to drop when disturbed and if the bucket is under them, they drop into the bucket. They die within a few minutes.
It is hard to believe that the first Japanese Beetle of the season was sighted a few short weeks ago on June 16, and that beetle was quickly squashed between Daniel’s fingers. Beetle season is expected to last a few more weeks and many leaves in the garden look, in Pearl’s words, like “lace doilies.”
For new readers, it should be noted that Daniel is against unnecessarily killing most insects, but Invasive Exotic species that have no natural enemies are fair game. Daniel dreads the eventual, inevitable introduction of the Spotted Lanternfly or White Cicada to his garden since they have already been reported from Pittsburgh, a mere 60 miles from Campbell.
Letter 3 – Bug of the Month July 2010: Japanese Beetles
June 24, 2010
Hi Daniel, You asked for images of Japanese Beetles. I had a few but none were very good, so I took some more today. Not really pleased with these either, don’t know why but my camera doesn’t seem to focus on them very well. Perhaps they are clear enough for an ID. I never cropped one very close to show the “lace leaf” you were talking about, this is a grape leaf. I hope you are able to use these. Thank you and have a great day.
North Middle Tennessee
Hi again Richard,
With all due respect, if you were our photography student, we would tell you that you are nuts. This photo has everything. We especially love that it shows the leaf damage caused by the beetle, which our mom in Ohio compares to lace doilies. The two pairs of beetles on the right appear to be mating. While the focus on the right of the image is not critically sharp, it is more than acceptable especially considering the detail in the Japanese Beetle in the upper left. We also appreciate that you managed to send us photos of all the insects we saw in Ohio earlier in the week that we lamented not having had a camera so we could take our own: The Question Mark, Great Spangled Fritillary, and Firefly as well as the Japanese Beetles. We are upgrading the status of this posting to the Bug of the Month for July.
We need to look for some good information on the control of Japanese Beetles for the gardening constituency of our readership.
Letter 4 – Enamored of the Japanese Beetle!!!
Name of Bug
Thank you for responding so quickly to my question about the caterpillar which turned out to be a white tussock moth caterpillar. Well, I was quite spellbound by the caterpillar. Was careful not to step on it, and watched out for it all day. Then I found out it could become a pest. Now, I have a bug I am wondering about (picture attached). Have not killed it, but am cautious about getting so enamored with it. Am glad to have found your site to ask questions. I began flower gardening this year and have found myself as taken with the animal life as the plant life growing around my yard. Meanwhile, I hope not to become a pest myself.
It would behoove you to try to erradicate the dreaded Japanese Beetle, an introduction that is very fond of roses, rose of sharon, and many other garden plants.
Letter 5 – Japanese Beetle
beetle that’s been seen eating roses
First I just want to say that I greatly enjoy your website, there are some fantastic pictures on there, and I could spend hours going through them all. Second, I’ve found a beetle that I don’t think I saw amongst the many pages of beetles you had represented. These were found on some rose plants on the campus of the University of Michigan, in Ann Arbor. They appear to have done quite a bit of damage to the roses, as you can see. Thanks in advance!
The Japanese Beetle was first discovered in this country in New Jersey in 1916 and has spread throughout most of the East where they have become a horrible pest. They are beautiful beetles that are hated by all rose gardeners. The grubs feed on the roots of grasses damaging lawns. You can purchase Japanese Beetle traps from a garden supply department.
Letter 6 – Japanese Beetle
Location: Wake Forest, NC
July 24, 2010 9:52 am
From Wake Forest, NC, this bug is pretty! I love the colours, but I had no idea where to start identifying on this one.
The Japanese Beetle, Popillia japonica, the species represented in your photograph, is currently prominently featured at the top of our homepage as the featured Bug of the Month for July 2010. WE got tremendous amusement at your infatuation with its coloration and your comment that it is pretty. It is an attractive beetle, but any points it might score in the beauty category would be quickly outweighed by its status as an invasive exotic species that swarms in the summer months and defoliates hundreds of different species of cultivated plants including roses, grapes, clematis, blueberries, peaches and almost any ornamental plant that is kept in home gardens. Our mother refers to the leaf damage as “lace doilies” since the beetles leave nothing behind on the leaf but the veins. We suspect that your letter might even generate some hate mail for gardeners who are plagued by the yearly appearance of swarming Japanese Beetles. Native to Japan, the Japanese Beetle was first found in New Jersey in 1916, and it quickly spread through most of the eastern parts of North America. Manufacturers even have products that are designed to attract and trap Japanese Beetles in an effort to keep them from feeding on cultivated plants. The adult beetles are not the only problem. The beetle grubs feed on the roots of plants and grasses, often causing brown lawns.
Letter 7 – Japanese Beetle
Bug on Michigan watermelon
Location: Mid Michigan
July 7, 2011 12:30 pm
Found this beautiful creature eating my watermelon plants.
Would like to identify, so I might find a way to ask it to leave.
Also, Bug pics are very hard to take! Links to Insect pic taking advice also solicited.
The invasive exotic Japanese Beetle was introduced to North America in the early 20th Century and it is well established in Eastern States where it appears in droves each year. It is doubtful it will ever be eradicated. Japanese Beetles feed on a multitude of cultivated plants and they are probably one of the most despised insects among home gardeners since they feed so indiscriminately. This is the first image we have posted of a Japanese Beetle this year.
Thank you sir.
Currently researching options. Have you recommendations?
Normally, we do not give extermination advice, but in the case of the invasive Japanese Beetle, we will make an exception. You can try hand picking them (careful, they drop to the ground when disturbed) and dropping them into a jar of soapy water. Adding a touch of oil or kerosene will also help. They quickly drown.
Letter 8 – Japanese Beetle
Bug of the month – Japanese Beetle
Location: Red Lick, Kentucky
May 1, 2012 7:02 pm
As someone who recently moved from the city (DC) to the country (Berea, Kentucky) I use your site constantly. I’ve been able to identify the critters I’ve been taking photo’s of since we moved here because of you so Thank You!
I am learning to live with my new neighbors though the adaptation is slow and difficult. This year I’m learning that some of the plants in KY are more vicious than the bugs.
Anyway I decided to donate to your site and also figured I’d throw in a photo of one of those nasty but beautiful Japanese Beetles I took last year since they’re your bug of the month this year.
I know it’s May 1st and I’m a bit late.
I have a quick question too, after finding out that we have loads of Forest Tent Caterpillars I was wondering what types of moths these little guys turn into? Sorry I dont have a photo… yet.
Signature: Micheal Mathews
We are happy to learn you find our site so helpful. Though we ran a tip on an organic method of controlling Japanese Beetles, we don’t expect to begin getting photos of them until mid June. We did feature them as the Bug of the Month in July 2010. You can find photos of the Forest Tent Caterpillar Moth on BugGuide.
Letter 9 – Japanese Beetle
Subject: Iridescent Beetle
July 1, 2016 9:58 pm
Hi! I’ve seen a few of these cool iridescent guys eating the leaves outside our garage, and I was wondering what they are. At first I thought it was a dogbane beetle? But to my knowledge those don’t have the white spots around their body’s like this one does. He sure was chomping away though!
Though it is a pretty beetle, the Japanese Beetle, Popillia japonica, is an invasive, exotic species that is the scourge of gardeners who grow roses. According to BugGuide: “Larvae feed on roots of many plants. Adults feed on foliage, flowers and fruits of various plants.”
Letter 10 – Japanese Beetle
Subject: Unknown beetle
Location: Pierrefonds, Quebec, Canada
July 22, 2016 2:15 pm
This beetle (and many others like it) have shown up in my uncle’s pool in Pierrefonds, Quebec, Canada. Any help identifying it would be appreciated. 🙂
Signature: Jeff Robinson
This is an invasive, exotic Japanese Beetle and we have already made a posting this year commemorating the 100 Year Anniversary of its accidental introduction. Most home gardeners in eastern North American are very familiar with Japanese Beetles, dreading their yearly appearance when they feed upon the leaves and blossoms of roses, fruit trees and many other cultivated trees, shrubs and flowers.
Letter 11 – Japanese Beetle
Subject: What is it?
Location: Northern lower michigan
July 12, 2017 5:07 pm
I planted a butterfly garden and today I found this little bugger tucked in between some leaves. Of coarse my concern is could he damage my milkweed or harm any eggs larvae or caterpillars? Is he ok or does he need to move it along?
Signature: May Cross
This is a Japanese Beetle, an Invasive Exotic species that is generally reviled among rose growers and other gardeners. According to BugGuide: “native to E. Asia, introduced in N. Amer. (NJ 1916, with nursery stock)” and “Larvae feed on roots of many plants. Adults feed on foliage, flowers and fruits of various plants. ” While they damage and defoliate many landscaping plants including roses, rose of sharon, grapes and fruit trees, we doubt they will trouble your milkweed as it has a noxious sap that causes most insects to avoid feeding on the leaves.
Letter 12 – Japanese Beetle Control
Japanese Beetle season holistic remedy
April 9, 2012 10:02 am
As we are swiftly approaching Japanese Beetle season here in the midwest, I thought your readers might be interested to know of a totally organic, all natural way of dealing with these destructive little buggers. I read in one of my Grandmother’s old cookbooks that these bugs come with their own repellent. You just take a handful of the beetles and squish them up, mix them with enough water to be sprayed, and apply the water/beetle juice solution to all affected areas. Apparently these guys can’t stand the smell of their own dead! I know you don’t normally endorse extermination, but sometimes the Japanese beetles get really out of control, consuming entire grape and raspberry vines, beautiful rose bushes, and other plants we’ve worked so hard on! Thanks for all the work you do on your wonderful site!
Sincerely from a long time fan of your site,
Signature: Amy Berogan
Thank you for this interesting remedy to the dilemma many home gardeners face when Japanese Beetle season begins in June each year. This invasive exotic species was accidentally introduced to North America in the early 20th Century on nursery stock imported from Japan and it has become one of the most despised insects among gardeners. Each year when the Japanese Beetles emerge, they feed on the leaves and blossoms of several hundred species of plants that are grown for agricultural and decorative reasons, including roses. We will post and feature your tip and run it through Japanese Beetle season this summer. We hope our readers will write in and comment if this remedy works. As a point of clarification, all reservations we have regarding Unnecessary Carnage do not apply to Invasive Exotic species that compromise native habitat and indigenous species. Since you did not supply a photo, we have included a photo of mating Japanese Beetles from our archive to accompany your submission.
That would be awesome and I am honored, special thanks to Grandma, of course. Incidentally, I was the person that sent in those inter-species mating photos last summer of the two Japanese Beetles with the Grapevine Beetle trying to squeeze his way in as well. Have a wonderful spring!
Wow, that photo is positively awesome.
Hey thanks!! I was out playing with the dog and just happened to look over on the grapevine to see the strange threesome…
Letter 13 – Japanese Beetle invades Canadian Garden!!!
Subject: Weird Beetle hundreds of them on the Tree
Location: Ottawa, On, Canada
July 7, 2012 12:27 am
I cant figure out what this beetle is? Its destroying my tree.. It also seems to mate on the tree leaves.. Legs don’t have a sticky grip to the leaves and falls off when branch shaken and fly briefly to another branch.
Based on your letter, we can think of three possible scenarios. Either you are new to gardening, new to Ottawa, or the Japanese Beetle has previously been absent in your area for some reason. Most gardeners in the northeast and midwest portions of North America (see BugGuide map) are very familiar with Japanese Beetles that appear each year in late June or early July and defoliate hundreds of different cultivated plants for the next six weeks or so. We don’t normally provide extermination advice, but we can assuredly tell you that the non-native, invasive, exotic Japanese Beetle is the scourge of many gardeners and we don’t have any problem with folks trying to control them, provided they do not use broad spectrum pesticides that kill beneficial insects as well. We support manual removal, however, earlier in the year, one of our readers supplied this wonderful natural means to control Japanese Beetles. Since we do not encounter Japanese Beetles in our Los Angeles offices and garden, we cannot vouch for this technique. Anyone who has had luck with this holistic remedy, please let us know.
Letter 14 – Japanese Beetles
I see you have a few pictures of these guys (Japanese Beetles) already, but they were just tearing up my friends roses and I wanted to share. They are so insidious!!! This photo was taken August 24th, in Lakeview Michigan, just north of Greenville. Thanks for your cool site ( love it )!
The Japanese Beetle is an excellent example of what happens when a destructive invasive exotic species becomes established elsewhere. Japanese Beetles appear in July and eat almost everything in their path until they are killed by the frost.
Letter 15 – Japanese Beetles
What is this bug, it is eating up my tree. I have thousands of them Thank you for your time
Mom in Ohio says the Japanese Beetles turn the leaves of her plants into “lace doilies” and your photo illustrates this nicely.