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
Identification
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
Lifecycle
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:
| Larvae | Adult Beetle |
|---|---|
| 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.
| Region | Quarantine/Regulation | Treatment Months |
|---|---|---|
| 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:
- Roses
- Sassafras
- Holly
- Birch
- Mountain ash
- Linden
- Maples
For crops and other landscape plants, they target:
- Grapes
- Beans
- Corn
- Garden vegetables
- Fruits
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 |
Control Methods
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.
Insecticide Applications
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
Pros:
- Kills larvae and adult beetles effectively
- Protects plants from damage
Cons:
- May harm non-target insects
- Requires regular applications
| Insecticide | Target Stage | Application Site |
|---|---|---|
| Imidacloprid | Larvae | Soil, lawns |
| Carbaryl | Adult | Plants, ornamentals |
Effective Traps
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
Pros:
- Reduces the adult beetle population
- No chemicals needed
Cons:
- May attract more beetles to the area
- Doesn’t address larvae in the soil
Bug Control Recommendation Tool
Footnotes
17 Comments. Leave new
Thank you for the identification. I hope my ‘pretty’ comment will be toned down some. I had no idea this bug was such an evasive critter. My apologies for making light of the damage this bug can do.
They might be pretty, but they love to eat my plants 🙁
We have what looks the same, eats and acts the same but not so brightly coloured. Red legs, brown to light yellow body. Would they be the Japanese beetle also?
Probably Rose Chafers.
If you would like any more photos of the Japanese Beetle, I have some great ones of a few mating pairs I took a few years ago at Sonnenberg Gardens in Canandaigua, New York. Let me know!
Thank you but we are not in need of any photos of Japanese Beetles at this time. We didn’t get (m)any reports of them this year.
More efficient still is squeezing them until the guts come out the rear when hand-picking them off — one at a time. It is also more humane (probably) and less wasteful of water, soap, and kerosene.
I believe I have substantially reduced the population near my house by using this method over the years. I have seen 4 all year, whereas 10 years ago, I would see 5-6 decimating a single rose leaf at the same time.
For the record, I don’t disturb any other beetles, unless I actively catch them eating leaves of my fruit tree. I have had rare occasions where a large number of June bugs seem to attack my cherry tree or peach tree. That, I could not abide.
More efficient still is squeezing them until the guts come out the rear when hand-picking them off — one at a time. It is also more humane (probably) and less wasteful of water, soap, and kerosene.
I believe I have substantially reduced the population near my house by using this method over the years. I have seen 4 all year, whereas 10 years ago, I would see 5-6 decimating a single rose leaf at the same time.
For the record, I don’t disturb any other beetles, unless I actively catch them eating leaves of my fruit tree. I have had rare occasions where a large number of June bugs seem to attack my cherry tree or peach tree. That, I could not abide.
We do not look down on folks who “manage” populations of invasive species.
I am overwhelmed by these beetles on my Petunias. They seem to be attracted to the white ones the most, although they are not fussy. I am ready to give up and afraid creeped out by these pests. Not into squishing them and spraying with them. Trying soap and water and after a treatment watching them land by the hundreds. Tired of it.
they are all over my rose bushes. ugh.. they ate them up. not happy.
Amy Berogan,
I find that squishing the bugs and spraying would absolutely ruin the fruit of my black raspberries and blackberries where I wouldn’t want to eat the berries. They even suck the berries leaving small holes.
Sevin works to kill them, but the spray also lands on the fruit. To die, they have to eat more of the leaf margins! I put out a trap made by Spectracide and it indeed catches them but I think the rose smell of the bait attracts even more. I’m thinking of having my lawn control place do the grub control to kill them at that stage.
I’ve even used a pair of plyers to squish them individually on the leaves. They are now eating my potato leaves and flowers and my yellow evening primrose.
I’m cutting down and killing my berry bushes if they are here next June. I’m in Indiana and I come from Colorado where I NEVER saw these bugs anywhere on anything!
Another nasty bug here is the stink bug! He loves berries too! I wish nature had a predator to eat these things but I’m sure birds don’t want that hard scarab outside in them.
They came from Japan on a shipment of iris in 1916 to New Jersey. (Wikipedia)
I hope a chemical company will come up with something to use that does not hard fruits.
Betty
Japanese Beetles have plagued gardeners in North America for over a century.
Amy Berogan,
I find that squishing the bugs and spraying would absolutely ruin the fruit of my black raspberries and blackberries where I wouldn’t want to eat the berries. They even suck the berries leaving small holes.
Sevin works to kill them, but the spray also lands on the fruit. To die, they have to eat more of the leaf margins! I put out a trap made by Spectracide and it indeed catches them but I think the rose smell of the bait attracts even more. I’m thinking of having my lawn control place do the grub control to kill them at that stage.
I’ve even used a pair of plyers to squish them individually on the leaves. They are now eating my potato leaves and flowers and my yellow evening primrose.
I’m cutting down and killing my berry bushes if they are here next June. I’m in Indiana and I come from Colorado where I NEVER saw these bugs anywhere on anything!
Another nasty bug here is the stink bug! He loves berries too! I wish nature had a predator to eat these things but I’m sure birds don’t want that hard scarab outside in them.
They came from Japan on a shipment of iris in 1916 to New Jersey. (Wikipedia)
I hope a chemical company will come up with something to use that does not hard fruits.
Betty
Hey Ya’ll….Greetings from Florida. I love this page. I also love bugs. When my son was little we would go out to our back yard at night with our flashlights to see what we could find. We have a spider here called an Ogre Face. It is so cool because they hold their web in their front legs and snag prey as it walks by. Thanks for this page. I will visit often. Laura Priest Jacksonville Florida.
Good morning Daniel. I a so happy to see you posting again! Did you know that they are edible, and an excellent protein source?
https://ironwoodforaging.com/blog/f/eat-japanese-beetles has more info, including how to harvest and prepare them. Don’t let inflation and supply-chain issues deprive you of healthy protein!
Thanks for the resource Daniel. We don’t think we will be putting Japanese Beetles on the menu this week but when food supplies dwindle, that information will help us to survive off the land.