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Posted 30 August 2013. PMN Crop News.

How to Spot and Control the Japanese Beetle

Source: United Soybean Board Press Release.

Chesterfield, Missouri (August 23, 2013)--The Japanese beetle is not considered a serious plant pest in its native country. However, since the pests were first discovered in the United States in 1916, they have become highly destructive, as well as difficult and expensive to control.


Managing the Japanese beetle in soybeans can be very challenging. Both the adults and larvae could potentially injure to crops. Adult beetles cause most of their soybean-yield damage through defoliation.

It is important to scout flowering soybean fields starting in early June into late July to determine the extent of defoliation. An adult Japanese beetle can be identified by the following characteristics:

Less than a half-inch long

Shiny, metallic-green body

Bronze-colored outer wings

White tufts along the side of the abdomen

The economic threshold for deciding whether to treat Japanese beetles is 30 percent defoliation before bloom and 20 percent defoliation after bloom. Some ways to detect and manage Japanese beetles include:

Japanese beetle traps. Helpful for detecting beetles and monitoring population fluctuations.

Control methods. Several potential options exist, including chemical controls, biological controls, or mechanical traps.