How to Kill Japanese Beetles

Co-authored by Rachel Cho

Last Updated: January 31, 2023 References Approved

Japanese beetles are the most widespread turf-grass pest in the US, mostly found in the Eastern and Midwest regions. They are a detriment to anyone's garden, as the adult beetles can consume the leaves and flowers of numerous types of plants. The larvae, which are called white grubs, feast on the plants' roots and can create dead patches on the grass. The adult beetles are a metallic green, and once they emerge from the ground in late spring or early summer, immediately begin feeding on your plants.^{[1]
X
Research source} Knowing how to kill Japanese beetles effectively and efficiently can prevent your prized plants from becoming beetle food.

Method 1

Method 1 of 2:

Removing Japanese Beetles by Biological or Chemical Means

1
Use nematodes to kill larvae. Nematodes are parasitic insect-eating round worms that feed on the grubs in the ground, providing an organic pest control method. Common nematode types include Steinernema Feltiae and Heterorhabditis bacteriophora.^{[2]
X
Research source} Place nematodes in the soil in late August or early September to begin treating the grubs for the next year. But you can apply nematodes as soon as there is evidence of Japanese beetle activity in your yard.^{[3]
X
Research source}
- Make sure the nematodes are fresh because they are living organisms. Water the ground before you spread them out, and keep the soil moist after you apply. You can also apply nematodes in mulch. For 50 or 100 million nematodes mix, use 1/2 teaspoon per gallon of water.
- Beneficial nematodes only attack soil dwelling pests, such as Japanese beetles, fleas, German cockroaches, termites, and ants. They are not harmful to people, animals, plants, or earthworms.^{[4]
  X
  Research source}
- You can purchase nematodes online, at garden centers, or at most major home improvement retailers.
- This method is effective for killing the pest in its larvae stage.
2
Chemically remove grubs with insecticides. You can spray the plants with Japanese beetle killer, found in most retailers and online. Sevin dust can also work, but it might kill beneficial insects along with the Japanese beetles.
- Some ingredients to look for when purchasing an insecticide are carbaryl, acephate, and permethrin.^{[5]
  X
  Research source} A Pyrethrin-based insecticide is a safe way to control pests on your plants while getting rid of other beetles in the process.^{[6]
  X
  Research source}
- Some insecticides are aimed at high Japanese beetle activity in your yard. Others are designed to be used in the early fall once the eggs have hatched and grubs are present. Make sure you read the label on the insecticide before you purchase it to find out what specific problem it targets.
Advertisement
3
Use organic neem-based insecticides. Neem oil is a natural pesticide that comes from the seeds of the neem tree, and is considered an anti-feedant because it reduces feeding of Japanese beetles when applied to the plants. Spray plants with neem oil to control the pests.
- Azadirachtin, one of the components of neem oil, can also repel and reduce the feeding of nematodes.^{[7]
  X
  Trustworthy Source
  National Pesticide Information Center
  Organization run by Oregon State University providing objective, science-based information about pests and pesticides
  Go to source} Use caution using neem oil if you have nematodes in your ground to combat grubs.
- You can purchase neem oil insecticides online and at most major retailers with a garden center.
4
Spray Japanese beetles with insecticidal soap. Soap-detergent sprays are contact pesticides, with no residual effects. They are similar to household detergents, but are specifically designed not to harm plants like household soaps can.
- When applying insecticidal soaps, you must thoroughly wet the pest. Most pests needs to be sprayed every 4-7 days.
- The ingredient you are looking for in a spray is potassium bicarbonate.^{[8]
  X
  Research source}
- Even soaps manufactured specifically for insects can harm certain plants. Check the label of the bottle, or do a test on your plant before spraying wide areas or repeatedly.

Method 2

Method 2 of 2:

Removing Japanese Beetles Through Other Means

1
Pick Japanese beetle adults from your plants. Japanese beetles can be easily removed from plants with your hands. After you remove the pest from the plant, drop it into a bucket of soapy water.
- Don't squish the beetle to kill it. Beetles attract more beetles through pheromones, which are so powerful they can attract beetles from a few thousand feet.^{[9]
  X
  Research source} If you squish a Japanese beetle, you run the risk of releasing the female beetle sex pheromone.
- This should be done early in the morning. Lay out a drop cloth and shake your plants, then dump the beetles on the cloth into soapy water.
2
Choose your plants carefully. Japanese beetles are attracted to certain plant species, so when you plan your garden, avoid plants that they will migrate towards. Carefully consult a list of susceptible plants, like this one from the Farmer's Almanac.
3
Cover your plants with a floating row cover. These covers allow sunlight, air, and water in, but keep beetles out. Make sure to keep the edges of the covers flush with the ground so no beetles can get through. If you already have a grub problem, avoid this method because it could potentially trap beetles inside with your plants.
- You can buy floating row covers online or at garden centers.
4
Keep your plants healthy. Japanese beetles are attracted to overripe and rotting plants.^{[10]
X
Research source} To avoid luring in beetles, harvest your plants regularly and try to keep them healthy.
5
Avoid Japanese beetle traps. These traps use pheromones and scented lures to attract beetles. Most research has found that traps attract more beetles to a yard than it actually traps.^{[11]
X
Research source} This means you are unnecessarily attracting beetles to your yard, resulting in a larger problem. Only use this method if you have a large yard and can place the trap a significant distance away from your garden.

Community Q&A

Question

What are some home remedies I can use to kill Japanese beetles?

Community Answer

Japanese beetles don't like neem oil. You can buy neem oil from a health food store or online from vendors like Amazon.
Question

We have 100's of Japanese beetles on our peach trees. They are on the peaches also. What is the most effective way to get rid of these beetles?

Community Answer

I believe you need to use a variety of measures. I have found spraying trees with Neem Oil and using physical picking of the beetles off of the trees work the best. The Neem can be used up until the day of harvest.
Question

Is Sevin dust harmful to honeybees?

Community Answer

Yes. Sevin, or any carbaryl insecticide, will kill bees. If this is a concern, avoid applying it to plants bees are likely to visit (those presently flowering).