Archive:Poplar/Poplar-and-Willow Borer
From Bugwoodwiki
From: Ostry, Michael E.; Wilson, Louis F.; McNabb, Harold S., Jr.; Moore, Lincoln M. 1988. A guide to insect, disease, and animal pests of poplars. Agric. Handb. 677. Washington, DC: U.S. Department of Agriculture. 118 p.
Contents |
Importance
Larvae of this weevil riddle the stems of young trees in plantations throughout north-central North America. Complete girdling kills the tree above the injury, forcing the tree to resprout multiple stems. Trees weakened by larvae may break.
Look For:
• Upper crown or the whole tree broken over or dead.
• Coarse, fibrous wood shavings on trunk either plugging or adjacent to a hole (up to one-fourth inch in the bark; the area below the hole may be moist from exuding sap.)
• White grub-like larvae, pupae, or black and white weevils (up to one-third inch long) in galleries in the wood. (Saw the injured portion of the stem longitudinally to see this.)
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| Larva of poplar-and-willow borer. |
Biology
Adults emerge from overwintering in the wood in spring, and soon afterward the female lays eggs in the stem in slits chewed into the bark. Young larvae first bore into the cambium around the stem, but as they grow they tunnel into the wood. When fully, grown, they pupate in enlarged galleries in the stem. Some pupae transform to adults that emerge in fall and lay more eggs; others overwinter and emerge as adults in the spring.
Monitoring
Inspect trees 2 years or older that are more than 1 inch in basal diameter. Begin in late spring to look for evidence of insect boring. Consider control if 10 percent of the trees are injured or if 1 to 2 percent of the trees die or break over.
Control
• In heavily infested areas, apply an insecticide recommended for wood-boring insects. Drench the main stem in late March or early April just before adults emerge. Repeat in July to kill summer-emerging adults.
• Avoid planting trees adjacent to heavily infested poplar, willow, or alder stands.
• Plant resistant clones.
• After harvest, remove and destroy any infested material to keep insects from reinfesting coppice or new planting stock.
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| Old canker and rough bark of affected stem. |
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| Wood shavings from poplar-and-willow borer gallery. |
For Additional Information:
Furniss, Malcolm M. 1972. Poplar-and-willow borer. For. pest Leafl. 121. Washington, DC: U.S. Department of Agriculture, Forest Service. 5 p.
Harris, John W.E.; Coppel, Harry C. 1967. The poplar-and-willow borer. Sternochetus (= Cryptorhynchus) lapathi (Coleoptera: Curculionidae), in British Columbia. Canadian Entomologist. 99: 411-418.
Smith, B.D.; Stott, K.G. 1964. The life history and behavior of the willow weevil Cryptorhynchus lapathi L. Annals of Applied Biology. 54: 141-151.
