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Japanese Beetle

Japanese beetle eradication project

The Japanese beetle (Popillia japonica) is a harmful invasive insect that poses a serious threat to Oregon and other western states. The largest infestation in Oregon was found in 2016 in the Cedar Mill, Bonny Slope, Oak Hills, and Bethany areas of Washington County.

This invasive insect can be destructive in multiple life stages. If it spreads widely in the state, it could destroy over 300 types of plants, leading to more pesticide use to protect crops and gardens. If we aren’t able to eradicate of the current population, the beetles will keep spreading, causing widespread destruction throughout Oregon and the western United States.

To prevent this, the Oregon Department of Agriculture (ODA) is working on a multi-year project to eradicate the Japanese beetles before they become established in Oregon. With help from local communities and municipalities, this project aims to protect Oregon’s agriculture and natural environment.

ODA will start its eighth year of beetle treatments in April 2025.



Identify a Japanese Beetle

The Japanese beetle has several unique features that make it different from other insects in Oregon and the western United States. Below is an image that shows how to tell the difference between the Japanese beetle and similar “look alike” insects.



Eradication Project

Invasive Species in Oregon
According to the ​Oregon Invasive Species Council​:
“Invasive species are animals, plants, and microorganisms that are not native to Oregon and once here can reproduce so vigorously that they replace our native species. They pose a threat to key sectors of Oregon's economy that depend upon natural resources and native ecosystems. Agriculture, forestry, tourism, and water resource infrastructure, including hydropower facilities, are at serious risk of being adversely impacted by invasive species. Unchecked, invasive species individually and collectively have the potential to imperil public health and to transform ecosystems, resulting in widespread economic and environmental devastations.”
Threat to Oregon
Like many invasive species, Japanese beetles don't have natural predators in the United States to control their population. In the Eastern and Midwestern U.S., these beetles cause large-scale destruction to garden plants and agricultural crops.
Since the Japanese beetle is a major threat to important industries in Oregon, such as nurseries, turf grass, and specialty crops, the Oregon Department of Agriculture (ODA) is working hard to stop the beetle from spreading by using quarantines and treatments. The overall goal of eradication is to protect Oregon’s farming and agricultural livelihood from harmful, invasive pests like the Japanese Beetle.
This invasive beetle can cause damage at different stages of its life. As a grub, it feeds on the roots of grasses, which weakens the plant and prevents it from getting enough water, creating brown or dead patches in lawns. As an adult beetle, it eats the leaves, leaving a pattern called “skeletonizing,” which causes the leaves to break down and fall off. Plants like roses, grapes, fruit trees, and berry bushes are especially vulnerable to this kind of damage.
When plants lose their leaves, they not only become more likely to get diseases, but they also become stressed, have higher death rates, and can’t make as much food through photosynthesis. Without photosynthesis, important environmental benefits like clean air, healthy water in rivers and streams, and temperature control through shade are also affected.
The Eradication Project
When a new invasive species is found, an eradication project may be initiated to remove all life stages of the pest (adults, larvae, and eggs) and prevent it from spreading. The methods used for eradication depend on the pest’s biology and characteristics. If we don’t get rid of the pest, it could become established and remain in the state forever. The sooner an invasive species is detected, the better. Sometimes, early detection can catch just 1-2 pests. Biological experts use risk models and their knowledge of insect biology to determine if an eradication project is needed to protect the state from the devastating effects of an invasive species. Early detection and prevention programs are a critical part of protecting our state from invasive species.
When the Japanese beetle population was discovered in the Cedar Mill, Bonny Slope, Oak Hills, and Bethany areas in Washington County, the population was small enough that it might still be possible to eradicate them.

Japanese Beetles on Your Property

In the fall, winter, and spring, Japanese beetles are in their immature "grub" stage and feed on grass roots, which makes it harder for plants to get water. Dead patches in lawns or grass may be a sign of Japanese beetle grubs. In the summer, adult beetles feed on leaves, fruits, or flowers (Japanese beetles love roses!). Visit the “Identify a Japanese Beetle” section above to help with identification.
If you live outside the treatment area and think you have Japanese beetles on your property, contact the Oregon Department of Agriculture (ODA) at Japanese.beetle@oda.oregon.gov to help with detection.
Note: Japanese beetles are often mistaken for boxelder bugs. If it's late fall and you're seeing many beetles inside your home, they are likely boxelder bugs, not Japanese beetles. Boxelder bugs are native to North America, not invasive, and aren't harmful, though they can be a nuisance as they look for warm places to stay for the winter. For more information on boxelder bugs and how to prevent them, check out the University of Minnesota Extension's guide.

Oregon Detections

The Japanese beetle was first discovered in the United States in a nursery in New Jersey in 1916. Since then, it has spread across the East Coast and Midwest, causing major damage to home gardens and crops. The beetles most likely arrived in Oregon when someone moved from an area already affected by Japanese beetles and brought a potted plant with them. Japanese beetle eggs and larvae live in the soil, which makes them easy to accidently transport without being noticed.
Things like plants, grass clippings, sod, and other yard materials can carry Japanese beetles from one region to another. To help prevent this, the Oregon Department of Agriculture (ODA) had previously set up a quarantine for yard debris in part of Washington County. For more details, check out the Yard Debris Quarantine section below.
There have been three separate beetle detections in Oregon in recent years:

  • Cedar Mill, Bonny Slope, Oak Hills, Bethany, Raleigh Hills, Cedar Hills, and Orenco in Washington County. These areas are where the largest and most widespread Japanese beetle infestation in Oregon was found in 2016. This population has since spread to areas of Multnomah and Clackamas counties but is actively being treated.
  • Oakland, Oregon, a small population of 10 beetles was found in 2017. By 2020, no beetles were detected. This population was probably started by a potted plant brought in from a Japanese beetle-infested area.
  • Portland International Airport. There is a constant risk of new Japanese beetles being brought in through cargo from infested areas. The airport is treated every year to prevent these beetles from spreading. For over 40 years, the ODA has been successful in keeping the beetles from reaching other parts of the state.

Japanese Beetle Treatment

What to expect from the main treatment
The Oregon Department of Agriculture (ODA) coordinates the treatment of irrigated grass and ornamental landscaped areas using a larvicide to kill Japanese beetles in their larval stage while they are still in the soil. This is an important part of the eradication effort.
Here’s how the treatment works:

  • ODA asks for consent from all property owners, including renters, in the treatment area. The project will be most effective if everyone participates.
  • ODA staff work with a licensed pest control company to apply a granular form of Acelepryn G to lawns and ornamental beds in the affected areas of Washington County.
  • Acelepryn G is a low-toxicity larvicide, meaning it is safer than other similar products. ODA follows the most recent safety guidelines when applying it. For more information about the larvicide Acelepryn G please visit the Oregon Health Authority’s Q&A page.
  • ODA has used Acelepryn G every spring from 2017 to 2024, with another treatment planned for spring 2025.
  • The entire treatment process takes about six weeks to complete for all properties in the area.
  • The treatment is FREE for all residents and property owners in the affected areas.
  • In areas with a high number of beetles, an extra foliar spray will be used. This spray has the same active ingredient as the granular treatment. Foliar treatments have been done since 2019 and are scheduled for summer 2025.

Treatment Schedule:
Treatments will take place between 8 a.m. and 5 p.m. There will be one granular treatment per property in 2025. If there are more beetles in your area, an extra foliar treatment may also be scheduled.
Who will do the treatment:
A professional, licensed pesticide applicator will perform the treatment. An observer from the Oregon Department of Agriculture (ODA) will be present. Only lawns and ornamental planting beds will be treated. Vegetable gardens, berry bushes, and other edible plants will not be treated.
How the treatment works:
The treatment involves applying Acelepryn G granular larvicide to lawns or ornamental beds. The application usually takes about 5 minutes, but it can take up to 15 minutes depending on the property. You do not need to be home for the treatment. If you won’t be home, follow the instructions below to prepare your property. Please make sure that your property is accessible to the treatment crew. Front and back yards need to be treated. All outside gates and entryways should be unlocked. Animals must be kept inside for the safety of our crew. Rescheduling properties for treatment at a later date is time-consuming and costly, and can reduce the efficacy of the treatment.
Weather Conditions:
The treatment is weather-dependent. If it rains heavily or the soil is too wet, the product may wash away and not work as well. Light rain is fine. If the treatment is delayed due to weather, we will notify you of a new date.
Before the Treatment:
On the day of the treatment, please:

  • Make sure gates and entryways are unlocked.
  • Keep pets inside for safety.
  • Remove or cover pet water and food bowls.
  • Move any items that can be easily moved off the lawn.
  • Keep children and pets inside during the application.

After the Treatment:
Water your lawn for 10-15 minutes to help the product reach the grass roots. If it has rained during or after the treatment, you don’t need to water.

  • Keep children and pets off the treated area until the granules are no longer visible.
  • Sweep or pick up any granules from walkways or patios after the treatment (wear gloves).
  • If you see a white marker flag, you can remove it once the treatment is done.

    • If you need more information, visit the Oregon Health Authority’s page on Acelepryn G.

Homeowner Consent Process

How to I consent to Treatment?
If you live in the treatment area, you’ll receive a notice via email or postal mail from the Oregon Department of Agriculture (ODA) with details about the program and a consent form. Treatment starts in April each year. Please return your signed consent form as soon as you receive it.
How Will I Be Notified?
You’ll be notified at least 72 hours before your treatment day. We will contact you via the phone number, text, or email you provide on the consent form.
Why Might I Need a Second Treatment?
If you’ve already had the granular treatment, you might need a second one. In areas with high beetle populations, we apply a foliar spray in addition to the granular treatment. The granular treatment targets beetle larvae, while the foliar spray targets adult beetles. Treating both life stages helps reduce beetle numbers and protects your garden from damage.​

Supplementary "Hot Spot" Treatment

“Hot Spot” Foliar Spray Treatment for High Beetle Density Areas
In areas with high beetle populations, we add a foliar spray (Acelepryn®) to the granular treatment (Acelepryn G®). This treatment is free of charge. The foliar spray uses the same active ingredient (chlorantraniliprole) as the granular treatment, meaning it has the same minimal risks.
Pesticide Information:
Acelepryn® is a “reduced risk” insecticide that targets pests feeding on ornamental plants, shrubs, and trees. When applied correctly, it is not considered a health risk to humans, pets, wildlife, or beneficial insects (like bees). For more details, click here.
Treatment Details:
The foliar spray, Acelepryn®, is applied to ornamental trees, shrubs, and plants and typically takes 10-15 minutes per property. Vegetable gardens, herb gardens, berry bushes, and other edible plants will not be treated. Once the spray has dried, it is safe to re-enter the treated area.​

Yard Debris Quarantine

Japanese beetle yard debris quarantine will not be enforced in 2025
Due to budget constraints the Oregon Department of Agriculture (ODA) cannot offer free yard debris collection and disposal services for residents living in the Japanese beetle yard quarantine. So instead, ODA is prioritizing pesticide application and trapping in infested areas. In addition, to help monitor any possible spread, ODA will increase the number of traps placed for detecting Japanese beetle in areas where yard debris waste is brought for disposal.
Thank you to those who supported the quarantine from 2017 to 2022. ODA asks for the public's continued support. The best way to help limit the spread of Japanese beetle currently is to ensure you are not moving any plant material, including outdoor potted plants, to new locations outside of Washington County. Also, please refrain from participating in any plant swaps if you are within the treatment area.
Residents in Washington County can continue to use their curbside yard debris bins as usual.
For more information on where to take your yard debris material (for those within a treatment area), please consult this list of participating disposal sites: Yard Debris Waste Disposal Sites in Washington County

Treatment Area Map

​Explore the 2025 Japanese Beetle Treatment Area

Use the map below to see if your property is in the Japanese beetle treatment area. In addition to Washington County and NE Portland, treatments have also been done in Oakland, OR, and at Portland International Airport in recent years.

2025 Treatment Area Map​​​​

Instructions for Using the Map:

  1. Click the button to access the treatment map.
  2. Once on the map, click the "Find address or place" icon.
  3. Enter your address in the search bar.
  4. A yellow arrow will appear, pointing to your address.
  5. If your address is within the treatment area, the map will show a blue outline and say, "Your property is located inside the proposed treatment area."
  6. If your address is outside the treatment area, the map will say, "No results found."

How You Can Help Protect Oregon’s Gardens and Agriculture:

If you live in or near the treatment area, your cooperation is key to protecting Oregon’s plants and economy. Here’s how you can help:

  • Report suspected Japanese beetles found outside the treatment area to the ODA.
  • Report any major beetle damage to lawns, roses, grapes, fruits, or other trees and shrubs, especially if it’s outside the treatment area.
  • Allow ODA staff to place traps on your property if requested during the summer.
  • Follow quarantine rules that prevent the movement of plants and soil from infested areas unless they have been certified as Japanese beetle-free or properly treated by state agricultural officials.​


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