News release: Japanese Beetles

Tim Baker, MU Extension Horticulture Specialist
102 N. Main, Suite 1, Gallatin, MO 64640
660-663-3232, bakert@missouri.edu

Release Date: July 19, 2018
Headline: Japanese Beetles

Last year, I wrote an article about Japanese Beetles. This non-native insect pest has been a problem in North America since it was introduced in New Jersey in 1916. It has been spreading slowly west through the years, and unfortunately is found in increasing numbers in our Northwest Extension Region.

Japanese Beetles are not picky eaters, and are known to feed on more than 400 species, including trees, shrubs, flowers, fruits, vegetables, field crops, and turf.  In high numbers, they can skeletonize leaves, resulting in a plant with only a framework of veins where the leaf should be.  Their grubs also feed on the roots of plants, including grass in lawns and golf courses.

Numerous complaints are coming in.  Two people, for example, have called me from Caldwell County and reported extremely high numbers on various types of plants.

One vineyard in Daviess County has experienced a high infestation for the second year in a row. Grapes are one of their favorite foods.

I also discussed the situation with Andy Luke, MU Extension Regional Agronomist in Bethany. He is seeing Japanese Beetles in almost every county he serves, mainly on soybeans. While they are not occurring in high enough numbers to cause significant damage, it is expected that the populations will build until they reach a point where control in necessary.

The two other horticulturists in our NW Extension Region are also reporting increased Japanese Beetle problems. Tom Fowler, Horticulture Specialist in St. Joseph, has been trapping them for years.  This year, he reports extremely high numbers in his traps.

Kathi Mecham, Commercial Horticulture Specialist in Carrollton, reports that some of the counties that have seen Japanese Beetle infestations in previous years vary in how hard they have been hit this year. But Ray County has especially been hit hard by Japanese Beetles this year.

Jennifer Schutter is a Horticulture Specialist in the Northeast Extension Region, headquartered in Kirksville.  She says that Japanese Beetles are bad in Audrain and Randolph counties, but they have also been reported in Lewis, Clark, and Adair counties. She also has a Japanese Beetle trap, but fortunately is not collecting the number that Tom Fowler is in St. Joseph. They have mainly been reported on grapevines and various ornamental plants. Unfortunately, their numbers are increasing each week.

Japanese Beetle adults are metallic green in color, with copper-colored wing sheathes on their backs.  On each side of their abdomen, they have six white tufts.  They are not large, typically measuring about 3/8 inch in length.

Insecticides are available to control Japanese Beetles, but they can be difficult to eliminate because of their potentially large numbers and ability to feed on so many different kinds of plants.  It’s best to use a liquid spray and apply it during the evening. Dusts can get on the hairs of bees and be carried back to the hive. So use a liquid, whenever possible.

For more information, I have included some links to several university resources on my web site.  Check them out at: http://extension.missouri.edu/nwhort/j-beetle.aspx