Aside from overly ripe and decaying fruits, favorite Japanese beetle foods abound in your garden. They're especially fond of flowers--any kind of flowers--particularly roses and the blooms of plum, linden and flowering crab trees. In all, about 300 plant species are eagerly consumed. Eggs laid in lawns and gardens in mid-summer hatch into hungry larvae that eat plant and grass roots before over-wintering. Grubs begin eating your plants by July, which is when you'll notice the evidence. That's when you need to be ready for action. Adult activity is most prevalent from mid-July through the month of August, or periods of "beetle flight." Try some homemade pest control methods that have proved to have some degree of effectiveness for battling Japanese beetles.
Plant varieties of flowers that attract Japanese beetles, but will kill when ingested by the insects. White geranium, red and dwarf buckeye, mirabilis and larkspur can be planted here and there throughout your gardening area to offer poisonous treats to beetles. Don't allow your children or pets around these plants.
Allow your lawn to dry out as much as possible between waterings. This deprives eggs of life-giving moisture, killing them.
Apply Neem oil to plants and soil as a repellent once weekly during active beetle months.
Add a generous squirt of hand washing dish detergent to a bucket of warm water very early in the morning, when Japanese beetles are still drowsy. Hand-pick the insects from your plants and drop them into the bucket. They soapy water will kill them.
Pour 1/4 cup hot water into an empty plastic milk jug. Add 1/4 cup sugar, cap the jug and shake vigorously to dissolve the sugar. Smash up about half of a ripe banana and put it in the jug. Shake well. Cover half the spout with tape to minimize the escape route and leave the cap off. Place the beetle trap well away from your prized plants. The banana will immediately begin to ferment, attracting Japanese beetles to it and away from your garden. They'll easily be able to enter the trap, but can't seem to figure out how to escape.