Japanese Beetles are not quick or easy to control. However, the USDA has developed an Integrated Pest Management Program (IPM) that combines biological, cultural, and chemical strategies. The Department states that the program will be effective "if homeowners are willing to monitor both adult and larval beetle populations closely and implement this program with neighbors and their local agricultural or horticultural organizations."

The first step in the program is surveying your property to determine the extent of infestation and need for control. (See Japanese Beetles and Grubs for survey techniques.) If you determine that control is needed, following is a summary of USDA control options:

 

Chemical Controls

A critical aspect of effective chemical control is correct timing and application. Always follow all label directions and consult any state regulations. Each State has its own agricultural chemicals handbook, which is updated yearly for appropriate control recommendations.

According to USDA, the following chemicals are a few of those that are effective for use in the control of the Japanese beetle adult and its grubs:

• Regulated chemicals for adult Japanese beetles: Acephate, Carbaryl, Malathion, Methoxychlor, Rotenone
• Regulated chemicals for Japanese beetle larvae/gubs include Imidacloprid, Bendiocarb, Isofenphos, Chlorpyrifos, Diazinon

For complete lists and details on chemical control, consult your local Cooperative Extension Service.

Before using any of these chemicals, check the label for particular formulations registered for Japanese beetles, read the entire label, and carefully follow application instructions regarding application methods and recommended rates.

 

Biological Controls

Another control option for Japanese beetles and grubs are biological-based approaches such as parasites, nematodes, and fungi – some of which are commercially available to homeowners; others are not.

These controls are slower acting than the chemical insecticides, but they last longer in the environment and do not have adverse effects on nontarget organisms.

• Nematodes. The most effective against Japanese beetle grubs are Heterorhabditis bacteriophora (which is commercially available in lawn or garden shops or by mail order) and Steinernema glaseri. Nematodes are live, have a fairly high oxygen requirement, and can survive for up to two months under cool conditions. Following accompanying directions, the nematodes are mixed with water then applied with a standard insecticide applicator.
• Bacillus thuringiensis (Bt). Bt is a natural soil bacterium that acts as a stomach poison when ingested, and can be used on the grub stage only. It is applied to the soil, with effectiveness relative to that of insecticides. For availability, consult your local extension agent.
• Milky Spore. Milky spore is the common name for spores of the bacterium Bacillus papillae; its name comes from the milky white appearance taken on by grubs that ingest the spores. Applied to soil, the spores are ingested by the grubs, germinate in the grub's gut, infect its cells, enter the blood and multiply; when the grub dies, it releases one to two billion spores into the soil. Because of this gradual build up of spores in the soil, this approach can be very effective long-term approach. Given 2 to 4 years, milky spore disease can suppress the development of large beetle populations. However, USDA notes that it works best when applied in communitywide treatment programs. For availability, consult your local extension agent.
• Parasites. Releasing natural enemies or parasites of the Japanese beetle has been proven to reduce populations. The two parasites that have been successfully established in areas of the U.S. inhabited by the Japanese beetle are Tiphia vernalis, a small parasitic wasp of the grub, and Istocheta aldrichi, an internal, solitary fly parasite of the adult. Although they are not yet commercially available, you can contact your local extension agent to inquire whether they are established in your area. If they are, ask for recommendations of plants that will attract the parasites to your property to help control the beetles and grubs.
• Habitat Manipulation. You can sometimes reduce populations by modifying your property so as to be less attractive to and suitable for the specific pests. For Japanese beetles and grubs, you can: plant resistant plant species; use mechanical traps to capture adults; keep trees and plants healthy so they are less susceptible to attack; remove prematurely ripened and diseased fruits that attract the beetles; focus on damaged turf grass that attracts females for egg-laying; cultivate non-preferred species of plants on your property – check with your local extension agent for such plants that do well in your area.

 

The complete document from which these USDA recommendations were summarized is available at Managing the Japanese Beetle: A Homeowner’s Handbook (pdf).