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1668 Lincoln Road (M-40 North) Allegan, MI 49010 |
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Maple Petiole Borer |
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The GATEWAY to Natural Resource Management |
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By Kelly Goward District Forester |
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Maple Petiole Borer
Don’t be alarmed if your sugar maple dropped some of its leaves this June. The culprit was a relatively harmless sawfly larva called the maple petiole borer. This introduced borer will attack all types of maples, but prefers sugar maple. Infestations are infrequent and unpredictable. The female sawfly deposits her eggs in the petiole, or stem, of the leaf where the larvae hatch and feed. Larval feeding severs the petiole and the blade falls. About 10 days later the petiole will fall and the larvae find their way into the soil where they pupate over the winter. Only one generation of larvae are produced each year. Typically, maximum leaf loss due to this borer is 25-30% of the total canopy, an amount that will have little impact on the tree’s health. Rarely is an infestation severe enough to warrant treatment; by the time the symptoms appear (leaf drop) it’s too late to treat anyway. Raking and disposing of the leaves will not do any good either, since the borer is found in the petiole. For more information, contact your local Conservation District – Ottawa: 616-846-8770 x5, Allegan: 269-673-8965 x3. |
