The twobanded Japanese weevil, Pseudocneorhinus bifasciatus is an invasive pest that has been in the U.S. for a century and is now found in Iowa. Individuals were collected in Ames, IA in early August.
Twobanded Japanese weevil adults have a broad host range and feed on the leaves of many common ornamental plants. Their feeding starts as notches along the margins of leaves and sometimes whole leaves are consumed. There are over 100 host plants including barberry, privet, lilac, rose, spirea, forsythia, viburnum, and euonymus.
Adult weevils are about one-quarter inch and are mottle brown in coloration. See photos below. Larva feed blow ground on plant roots. In Iowa it is most likely there is only one generation per year with adults appearing in late June to early July.
Leaf damage by adults will be primarily cosmetic and management is not necessary for most homeowners.
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