Japanese beetles are a serious pest in America. Though they have many natural enemies in Japan, they don't have the same kind of balance here, and they are capable of great crop destruction. What's more, they leave hormones on plants they've visited, which attracts even more Japanese beetles. Fortunately, there are many effective homemade Japanese beetle remedies.
One of the most effective home-based pest controls for Japanese beetles is canola oil. This common kitchen ingredient can be used to effectively kill Japanese beetles in no time. Take 1 tbsp. canola oil and mix it into a quart of water. Add a few drops of liquid dish soap to add a slight poison to the mix. The soap won't kill your leaves, but will affect the beetles. Put the mixture in a spray bottle and spray your plants from the top, making sure to get it on as many leaves as you can. Make sure to spray the roots and underside of each plant, too. The canola oil will stick to the outside of the Japanese beetle and will cause it to suffocate. The dish soap also will poison them slightly and cause confusion.
Another effective way to control Japanese beetles is to use plants that repel the beetle naturally. Plants that will repel Japanese beetles include catnip, chives, garlic, tansy and rue. The problem is that some of these plants, like catnip, are actually weeds that will suck up water and nourishment from the surrounding plants. It may be more effective to spread leaves of catnip and cloves of garlic around your garden. You can also mix small amounts of ground tansy and rue with water, then spray this mixture on your plants. Using a combination of these plants should keep Japanese beetles away from your garden.
One of the most effective baits for Japanese beetles is a banana. They simply cannot resist the sweet taste. Mix 1 cup water, 1/4 cup sugar, a mashed banana and a package of yeast in a gallon milk jug. Make as many of these as you want, and place them around your garden. As the mixture ages, it will begin to ferment and create a pleasing odor for the insect. The Japanese beetle will then crawl into the jug but will be unable to find its way out, as Japanese beetles are notoriously bad fliers. The paste will stick to its legs and weigh it down, further complicating its escape.