Every year in our gardens and landscapes, we have unwanted visitors that show up and leave a big mess. They eat just about everything in sight, and leave our plants in bad shape.
Sid Mullis, Augusta-Richmond County's extension agent, started getting calls last week about Japanese Beetles. So far, I haven't seen any or gotten any calls about them, but it is time for them to emerge.
Japanese Beetles were introduced into the United States in 1916 in New Jersey. Since then, they have spread to all the northern states, mid-western states, and to the southern states. In Georgia, they are found north of the fall line. They tend to like heavy soils such as clay over sandy soils. However, some Japanese Beetles have been found south of the fall line.
I found my first Japanese Beetles in my garden in 1996, and the numbers have steadily increased since then.
Japanese Beetles are very striking insects. They are colored a bright metallic green with coppery brown forewings that reach almost to the tip of the abdomen. There is a row of five white spots along the side of the abdomen and a pair of white spots on the top of the last abdominal segment. The spots help distinguish from similar ones such as the Green June Beetle.
Japanese Beetles have a preference for what type of plants that they like to eat. Two of the plants that they are their favorites are roses and crape myrtles. Other plants they will eat are hibiscus, apples, pears, plums, and many of the vegetables, especially beans. The damage is very easy to recognize. They eat the tissue between the veins. The leaf will have just a skeleton of veins left. Also, they will eat flowers. The larval stage, which is a white grub, will eat the roots of plants. They can be a major pest of turfgrass.
In order to control Japanese Beetles, we must understand their life cycle. There is one generation per year. The adults emerge in late May or June and can be active until July. The adults will live four to six weeks with the females laying eggs during most of their lives. The eggs hatch in two to three weeks.
The grubs feed on the roots of plants and will become mature grubs by early fall. The grubs over-winter in the soil, and in the spring they pupate and become adults. Then the cycle begins over again.
To control Japanese Beetles, you need to control the adults and the white grub stage. There are a number of ways that you can control the adults. First, you can hand pick them when you first see them in your garden. I use a bucket that has soapy water in it. I then knock the beetles into the water.
To control the grubs, we have two windows when the treatments work best. The first is late August through September. The other time is in March. The grubs are closest to the soil surface at this time.
There is an organic control option available and this is a fungus that you apply called milky spore. The fungus in milky spore is Bacillus popilliae. You can find this in stores or you can order it online. There are insecticides that you can use to control the grubs. These products control other grubs besides Japanese Beetles. Some of the products are imidacloprid, trichlorfon, and halofenozide. These can be found in most garden centers. You need to read and follow the labels on all pesticide products.
There is one control option that I would like to caution you about. We do not recommend the use of Japanese Beetle traps. These traps have sex pheromones in them. These traps will trap the beetles, but they will draw them to your yard. The beetles can fly in from as far as a quarter of a mile away.
By scouting your yard and starting an early control program, you can have success on controlling the unwanted Japanese Beetles.
Columbia County Extension Agent Charles Phillips can be reached at (706) 868-3413 or by e-mail at firstname.lastname@example.org. The Extension Web address is www.ugaextension.com/columbia.
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