It is believed that the Japanese beetle (Popillia japonica Newman) was brought into the United States in 1916 from Japan. The beetle has quickly spread and become a major pest. Adult beetles feed on several hundred varieties of plants and control efforts cost an estimated $460 million a year, according to the United States Department of Agriculture. The beetle grubs also cause widespread devastation to lawns and the roots of plants with their voracious feeding habits. Control can be obtained through diligent management efforts.
Apply the nematode Heterorhabditis bacteriophora to lawns infested with the Japanese beetle grub. The nematodes will help to control the beetle grub. Purchase the nematodes at select garden centers or online. The nematodes will need to be mixed with water and applied to the grass using a pump garden sprayer. Follow the directions on the nematode container for application.
Apply an approved pesticide known to be effective on grubs, such as imidacloprid or halofenozide pesticides, in June and July to lawns that show infestation. Follow the directions on the label for application. Water thoroughly after all pesticide applications.
Pick adult Japanese beetles from the foliage of infected plants. Deposit the beetles into a mixture of 25 percent dish soap with 75 percent water to kill them. If the infestation is severe, hold a pan below the plant and gently shake the plant so the beetles fall into the soapy water and drown.
Spray the foliage of plants infested with adult Japanese beetles with carbaryl, acephate, permethrin or cyfluthrin, which are approved pesticides known to be effective on adult Japanese beetles. Apply according to the directions on the pesticide label. Most applications will last between two to three weeks and then will need to be reapplied. Use a garden pump sprayer for applications.