How to Prevent Japanese Beetles
- 1). Treat your lawn or garden for white grubs that will become Japanese beetles as soon as you notice them feeding. These small white worm-like creatures are shaped like the letter "C" and usually begin to feed in May and June.
- 2). Add worms called beneficial nematodes to your soil to attack and control grub populations. Nematodes are already present in soil and prey on white grubs and other insects that can be a threat to plant life. Adding more nematodes is an easy and environmentally friendly way to prevent grubs from turning into Japanese beetles. Visit your local garden center to order nematodes and release them into your garden every month or so until the grubs are gone.
- 3). Choose a chemical application to get rid of grubs before they become beetles. Many pesticides kill grubs and adult Japanese beetles on contact, but may be harmful to nearby plant and animal life. The University of Minnesota Extension can help you choose a safer, effective pesticide (see Resources).
- 4). Make your garden unattractive to the pests. Avoid planting trees that the insects feed on, such as American elm, American chestnut, crabapple, black cherry, walnut and black oak. If this isn't possible, interplant flowers and herbs that repel the beetles, such as garlic plants, white mums and citronella.
- 5). Control small patches of Japanese beetles by spraying them with a water-and-dish-detergent mixture. The force of the soapy water knocks them off the plants and repels them on contact. Hand-held vacuum cleaners can be an effective removal tool as well. Dump the stunned beetles into a garbage bag or elsewhere where they can do no more harm.
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