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Japanese Beetles in Kansas City

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When a horticulturist is asked, “Do we have pest XYZ here?” many times they will reply, “Well, not yet, but it is only a matter of time.” With that thought in mind, I have been asked for years about the Japanese beetle in Kansas City. Japanese beetles have been defoliating plants in the eastern United States, slowly working their way west.

When I started in Extension a number of years ago, that was my standard reply. Well, time is up. We now have Japanese beetles. They hit KC around 2009.

How to Identify Japanese Beetles
Japanese BeetlesJapanese beetles can be troublesome on two fronts. The adults feed on a wide variety of plant materials including: rose, grape, crabapple, linden and birch. The grub can be a pest of the lawn, feeding on the roots.

What people are detecting is the adult stage, which is active for about six weeks in the summer. The adult is less than ½ inch in length, and metallic green in color with coppery wing covers. The most identifying marking is white tufts of hair that protrude from the end of the abdomen. For the average person, that means white dots on the side of the small beetle. The larvae are a white grub that looks much like the other grubs found in our area. Identification of the Japanese beetle will require a microscope and a close up look at the hair patterns on its butt. I am going to assume most of you will leave anal inspection to the trained professional. I can hardly wait for your sample!

Japanese Beetle Damage
Japanese Beetles on rose budsDamage from the adults is defoliation of the host plant. The good news is, many well established plants will be able to tolerate minor feeding with no loss in vigor. The feeding tends to be more in mid to late summer, which means the plant has had more time to store food reserves for next year.

Controlling Japanese Beetles
Japanese Beetles in a bucket of soapy waterOptions for control range from doing nothing to hand removal or chemical sprays. They often feed in clusters, so knocking the adult beetles off into a bucket of water or alcohol with kill them. Chemical sprays such as Sevin or cyfluthrin are effective and will last for up to two weeks. The disadvantage of spraying is the removal of beneficial insects from the plant that can control other pest such as spider mites.

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