![]() ![]() If you missed these opportunities and you find yourself dealing with a shrub with skeletonized leaves (the most common situation), there are other treatments you can try. In early spring, you can also try a dormant oil treatment, but selective pruning is more effective. When the shrub is leafless, therefore between late fall and early spring, take a pair of pruning shears and inspect all the stem tips, removing and destroying those that bear the characteristic straight row of brown bumps, very literally nipping the infestation in the bud. If you really want to stop a viburnum beetle infestation, you really have to be proactive. A single female can lay up to 500 eggs per season.Ĭonventional Treatments Egg cases are most visible when the shrub is leafless. Throughout the summer, females lay eggs in single file on stem tips, mostly on lower branches, covering them with a little dome of chewed bark and excrement. They keep feeding well into autumn, until the first killing frost. ![]() They are gray-brown elongated beetles, 4.5 to 6.5 mm long, and recall a lily leaf beetle in shape. Towards the end of June or in July, the adults emerge, climb back onto the shrub and start eating the leaves in their turn. In early to mid-June, they drop to the ground at the base of the shrub and begin pupating just below the soil. They look like small yellow to pale green caterpillars covered with black dots, measuring only 10-11 mm long. ![]() The larvae hatch around May from eggs that overwintered on twigs of the host plant and immediately begin to eat young viburnum leaves. If a shrub is attacked severely every year for 2 or 3 years, it may die. dentatum), two native North American shrubs. opulus americanum) and arrowwood viburnum ( V. However, it will also attack other viburnums, including American highbush cranberry ( V. opulus ‘Sterilis’), with its rounded balls of flowers. The beetle’s primary host is the guelder rose or European highbush cranberry, Viburnum opulus, especially the highly popular snowball bush ( Viburnum opulus ‘Roseum’, also sold under the name V. Both adults and larvae feed on viburnum leaves, ensuring a long season of continuing damage. If your viburnum is suffering from viburnum leaf beetle, you’ll know it: it skeletonizes leaves, leaving only the veins. They belong to the brand-new Adoxaceae family, recently separated from the Caprifoliaceae (the honeysuckle family). There are some 150 species, mostly from the temperature regions of the Northern Hemisphere, with a few species straggling down into Africa and South America at higher latitudes. Viburnums are abundantly found in the wild, but are also popular garden shrubs, grown for their clusters of (mostly) white spring flowers, often beautifully textured leaves and colorful fall berries. It’s now common throughout Northeastern North America and is now spreading on the West Coast as well. It was accidentally imported into North America in the 1940s, but only began to spread widely in the 1970s. If the leaves of your viburnums look like they’ve gone through a leaf shreader, you can be sure they’re under attack from the viburnum leaf beetle ( Pyrrhalta viburni), This small, elongated beetle is native to Europe and Asia. A skeletonized viburnum leaf is a sure sign of viburnum leaf beetle. ![]()
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