VIBURNUM LEAF BEETLE, Pyrrhalta Viburni, (COLEOPTERA: CHRYSOMELIDAE)
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Rose Hiskes, Diagnostician and Horticulturist Department of Entomology The Connecticut Agricultural Experiment Station 123 Huntington Street, P. O. Box 1106 New Haven, CT 06504 Phone: (203) 974-8600 Fax: (203) 974-8502 Founded in 1875 Email: [email protected] Putting science to work for society Website: www.ct.gov/caes VIBURNUM LEAF BEETLE, Pyrrhalta viburni, (COLEOPTERA: CHRYSOMELIDAE) Images by Timothy Abbey, Richard Cowles and Rose Hiskes The viburnum leaf beetle was first found in straight rows of cavities on the undersides of Connecticut in 2004. Yellow to brown terminal twigs. They lay multiple eggs in adults are approximately ¼” long and feed the cavities and cover them with a mixture on foliage of thin-leaved viburnums from of feces and shredded bark (Figure 3). July to September (Figures 1, 2). During the Flattened brown-spotted yellowish larvae summer and fall, mature females make hatch mid-May the following year and feed VIBURNUM LEAF BEETLE, Pyrrhalta viburni, (COLEOPTERA: CHRYSOMELIDAE), Rose Hiskes, The Connecticut Agricultural Experiment Station, www.ct.gov/caes 1 on the emerging leaves (Figure 4). As a Highly susceptible group, they skeletonize leaves beginning on V. dentatum, Arrowwood viburnum the undersides, but as larvae, they increase V. nudum, Smooth Witherod in size. Then, they begin to eat through the V. opulus, European cranberrybush entire leaf, leaving only the veins. viburnum Approximately a month later, they crawl to V. opulus var. americana (formerly V. the ground to pupate in the top 1 – 2 inches trilobum), American cranberrybush of soil. Adults emerge in three to four viburnum weeks (July), feed, mate and begin laying V. rafinesquianum, Rafinesque viburnum eggs in the twigs. Initial feeding by adults results in oval holes in leaves that can Susceptible progress to total defoliation. There is one V. acerifolium, Mapleleaf viburnum generation each year. V. lantana, Wayfaringtree viburnum V. rufidulum, Rusty blackhaw viburnum When noticed, larvae and adults can be V. sargentii, Sargent viburnum handpicked. Twigs with eggs can be pruned V. wrightii, Wright viburnum off during the winter months when they are most visible. Azadirachtin, which is among Moderately susceptible the compounds registered for use against V. alnifolium (syn. V. lantanoides) this pest in Connecticut, will control small Hobblebush larvae and repel adults. Bifenthrin, V. x burkwoodii, Burkwood viburnum permethrin, and rotenone can also be used. V. cassinoides, Witherod viburnum Multiple applications are often necessary. V. x carlcephalum, Carlcephalum viburnum Imidacloprid applied as a systemic to be V. dilatatum, Linden viburnum taken up by the roots may provide season- V. farreri (‘Nanum’ is highly susceptible) long control. Consult the label for dosage Fragrant viburnum rates and safety precautions. V. lentago, Nannyberry viburnum V. macrocephalum, Chinese snowball Probably the most important control viburnum measure for viburnum leaf beetle will be to V. x pragense, Prague viburnum plant species that are resistant to feeding by V. prunifolium, Blackhaw viburnum this pest. While at Cornell University, Dr. V. rhytidophylloides,Lantanaphyllum Paul Weston rated viburnums for tolerance viburnum to viburnum leaf beetle (www.hort.cornell.edu/vlb/index.html). Resistant Highly susceptible and susceptible species V. bodnantense will die following approximately three V. carlesi, Koreanspice viburnum successive years of defoliation. V. x juddii, Judd viburnum V. plicatum, Japanese snowball viburnum V. plicatum f. tomentosum, Doublefile viburnum V. rhytidophyllum, Leatherleaf viburnum V. setigerum, Tea viburnum V. sieboldi, Siebold viburnum VIBURNUM LEAF BEETLE, Pyrrhalta viburni, (COLEOPTERA: CHRYSOMELIDAE), Rose Hiskes, The Connecticut Agricultural Experiment Station, www.ct.gov/caes 2.