Japanese beetles found their way into the United States in 1916. They are very destructive insects that have created serious problems for agriculture, especially in the eastern states. Both the adult beetles and their larvae eat hundreds of types of plants. Adult beetles eat primarily leaves, while the larvae, or grubs, favor plant roots and grasses, including lawns. If you live in the eastern United States and see half-inch beetles with a metallic green, shiny body and bronze colored wings, you've got the Japanese beetle. But hope---and help---are at hand.
Set traps containing a pheromone and a floral lure to assess the size of your beetle population. If your trap fills in one day, this indicates you have a beetle problem. If you trap only a handful of beetles on the bottom of your trap over one week, your problem is not severe. Also, dig several soil samples in brown areas of your lawn to determine the extent of grub damage. Continue using traps with a pheromone throughout the summer; traps are available at nurseries and garden centers.
Apply the soil bacterium Bacillus thuringiensis to lawn areas to kill grubs, making certain you follow package instructions.
Apply the bacillus called milky spore powder to lawns where you have found Japanese beetle larvae.
Spray adult beetles with commercial sprays that contain neem, pyrethrin or other natural products.
Grow plants that attract natural predators of the Japanese beetle. Some parasitic wasps exist in regions where the Japanese beetle lives: check with your agricultural extension to learn if these beneficial insects already live in your neighborhood and what you can plant to attract them.