I saw my first Japanese Beetle last week on a Zinnia in Maryanna's flower garden. My first sighting is always a red flag and honestly, I'm surprised it was mid-June before one appeared.
Japanese Beetles are believed to have made their way into the United States in the early 1900s on Irises imported from Japan. At the time of their arrival, we were unaware of the fact they had hitched a ride to the states but around 1919, the first were documented in New York City. Ever since, they have been migrating to warmer climates.
When they first hit any area, it's common for communities to look for ways to eradicate themselves of the plant-destroying insects. Japanese Beetle traps are one method of eradication, but create more problems than they solve many times.
I will say that the Japanese Beetle trap is very aggressive in catching Japanese Beetles. They will keep you busy as long as you want to be. People have filled trashcans with hundreds of them. The problem with the Japanese Beetle Trap is that it seems to draw the insects for miles and miles. Your neighbor will appreciate you taking his Japanese Beetles away for him.
Japanese Beetles seem to especially like roses, purple plum trees, any purple foliage plants and some garden vegetables. Pole beans and sweet corn seem to be their favorites.
Pole beans such as Kentucky Wonder, White half runners or most Italian-style green beans seem to be the most affected. If you grow Pole Beans, you will need to check them every day and sometimes twice a day. You can walk through the garden in the morning and come back that afternoon to find a huge infestation of these Japanese Beetles on your plants. They can completely destroy the foliage in quick order, so spraying them is very important.
Corn seems to be most at risk when the ear is developing. The insects like to consume the silk at the top of the ear. This can damage the ear if it occurs during the first five days of pollination. Most of the time, pollination has already occurred and no damage is done to the ear of Sweet Corn. Still it is unsightly to see a bunch of Japanese beetles hanging on an ear of corn.
There are a number of things that you can do to fight the infestation of Japanese beetles. One method is to keep a five gallon bucket that is half full of soapy water near your garden. You can place the beetles in the soapy water to eradicate them. It can be difficult to catch them, the beetles will fly away when they are disturbed. Other organic methods include spraying with Neem oil. Sprays containing potassium bicarbonate are also somewhat effective.
If you are wanting something stronger that is not organic I recommend Liquid Sevin which can help with serious infestations. You may want to keep your sprayer handy and be ready to attack on a moment's notice. Be cautious to always follow safety directions when using this product.
Typically, as we go through the season the Japanese Beetle numbers seem to decrease. From my experience, the next three weeks will be the most serious. The main thing to remember is to check your garden or landscape at least once a day to see if you have any. Happy Gardening!