Japanese beetle: Injury and damage

Japanese beetle injury: Leaf defoliation of 10% [left], 16% [center], and 25% [right] caused by adult Japanese beetles, Popillia japonica. (Photos Marlin E. Rice)Japanese beetle injury: Leaf defoliation of 10% [left], 16% [center], and 25% [right] caused by adult Japanese beetles, Popillia japonica. (Photos Marlin E. Rice)

Injury by Japanese beetles is not common in Iowa soybeans. When injury does occur, it can best be identified by the skeletonization of leaves. That is, the beetles eat the softer leaf tissue but usually avoid feeding on even the smallest leaf veins, thereby leaving a leaf “skeleton.” Injury to Iowa soybeans is most likely to occur in fields with sandy soils and has in recent years been reported near Cedar Rapids and along the Mississippi River.