Japanese beetles on the rise in Missouri
Japanese beetle populations in Missouri are likely to increase exponentially in the coming year, says an entomologist for University of Missouri Extension.
For the past year, researchers have been monitoring the beetles' numbers at the A.L. Gustin Golf Course near MU Faurot Field, said Wayne Bailey. During that time, the number of beetles collected weekly has increased from 10 to 15 to more than 1,000.
The beetles are still in the colonization stage in Missouri, Bailey said. Numbers will grow over the next seven to 10 years throughout the state before beneficial biological pathogens and agents will slow population growth.
The Japanese beetle was first found in the U.S. in 1916, possibly arriving in shipments of irises from Japan. It made its way to Missouri by 1934 and stayed primarily in urban areas through the 1960s, living primarily in golf courses and plant nurseries where grubs of the pest were brought in with soil.
Adult Japanese beetles are about a half-inch long and metallic green in color with bronze- or copper-colored wing covers. Groups of beetles feed on corn's green silks and tassels, foliage of soybeans, and the fruit and foliage of more than 400 flowers, shrubs and trees.
When feeding on corn silks and tassels, the beetles disrupt pollination and reduce yield, leaving ears with just a few kernels. Feeding on soybean and corn leaves by grubs often damages plant root hairs, resulting in poor uptake of water and nutrients, and poor stands.
Linden trees also are especially susceptible to damage by Japanese beetles.
For more information and insecticide guidelines, go to ipm.missouri.edu and enter "Japanese beetles" in the search box. Wayne Bailey talked about Japanese beetles in a 2011 MU Extension news video, which can be viewed at http://youtu.be/IQS2vgKPzXA.