Japanese beetles (Popillia japonica) are an invasive species that feed on the leaves, flowers or fruit of more than 275 species of plants, especially plants in the rose family. Grubs (larve) feed on the roots of turfgrasses such as Kentucky bluegrass, fine fescues, ryegrasses or bentgrasses causing the turf to brown and die.
According to the University of Maryland Extension, although several species of birds feed on adult beetles, their efforts are insufficient to prevent injury to ornamental plants, and even the best insecticides will only provide temporary relief when adult populations are heavy. Unfortunately, most pesticides remain toxic only for a few days and any new plant growth will not be protected. Due to the continuous migration of beetles, 2 or 3 spray applications may be needed to prevent serious injury to plants like roses and grapes. Fortunately, many foliage plants will tolerate moderate defoliation.
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