Elderberry borer (Desmocerus spp.)
Pest description and damage The immature roundheaded borer that matures to a reddish cerambycid beetle with a black thorax and head is found on elderberry in Washington and is associated with round exit holes surrounded by shattered bark of the stems of this shrub. With the increase of ornamental elderberry cultivars, there are more reports of wilting canes and even death of shrubs. Canes start to wilt at the tips with damage continuing down the canes. Infested canes are lumpy and round exit holes with shattered bark are visible.
Biology and life history Little is known of this beetle. Both the borers and adult beetles are found associated with elderberry in the Cascade Mountains and along Puget Sound and Willapa Bay in Washington. One observant horticulturist said that damage begins with wilting tips, suggesting eggs are laid at the tips of canes and as the larva burrows downward, the cane wilts further.
Pest monitoring Watch for the first signs of wilted tips in spring. Cut well below the wilted area and inspect for the larva by splitting the cane.
To control larvae boring through the cane, remove the cane just below the wilted portion when symptoms are noticed.
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