How Can I Control Adult Japanese Beetles?

Do you want to control Japanese beetles using the biological control method?

Do you want to control Japanese beetles using low-risk (organic) insecticides?

Do you want to control Japanese beetles using synthetic insecticides?

Do you want to use residual, foliar sprays?

There are few natural enemies of Japanese beetles released in the US. The fly Istocheta aldrichi lays eggs on adult Japanese beetles in summer, whereas the wasp Tiphia vernalis parasitizes grubs in the spring. Although both natural enemies became established in parts of the US, neither is very abundant and they have little impact on Japanese beetle populations.

Products containing pyrethrins are somewhat effective contact insecticides provided they are sprayed directly on the insect. Repeat applications are necessary. Avoid spraying bees and beneficial insects as these products are toxic to these non-pests as well. Neem oil is effective for several days but repeat applications are necessary. Neem oil helps deter Japanese beetles but is less effective when large numbers are present. Bacillus thuringiensis galleriae (BeetleGone, BeetleJus) is moderately effective against Japanese beetle adults, giving one to two week’s protection. This product is not toxic to bees and other beneficial insects.

Several effective, longer-lasting insecticides are available for treating Japanese beetles. Chlorantraniliprole provides two to four weeks of protection and is low risk to bees. Pyrethroids, including bifenthrin, cyfluthrin, lambda-cyhalothrin, and permethrin, last about two to three weeks. Carbaryl or acephate will provide one to two weeks’ protection. Pyrethroids, carbaryl, and acephate are toxic to bees and other pollinators. Always follow the pesticide label directions attached to the pesticide container you are using.

Systemic (absorbed by one plant part and moved to leaves and other plant parts) insecticides for use on landscape plants include imidacloprid and dinotefuran, both neonicotinoids. They are applied to the soil and only one application is needed per year. Do not apply to the soil within 4-5 feet of pollinator attractive plants. Always follow the pesticide label directions attached to the pesticide container you are using. Be sure that the plant you wish to treat is listed on the label of the pesticide you intend to use.

Physically removing beetles is a practical and effective management practice for smaller landscapes or a few plants, especially when only small numbers of Japanese beetles are present. Handpick or knock the beetles into a bucket of soapy water to kill them. Check your plants daily and remove any beetles that you find to minimize feeding damage. The best time to remove Japanese beetles is in the evening or the morning when beetles on the plants are still cool and sluggish.