I need some help here! (insect ID)

Question: I live in Highland. Up until Monday, this bush was healthy and greening up nicely. The leaves were bright green, everything was great...this morning, I was watering and I found the bush in this condition. It's covered in these little larva and the leaves have turned to brown lace. There's nothing left but a few green leaves and those are now covered with the larva. I've never had this happen in the ten years we've been here. Can you tell me what they are, if it's treatable and if the bush is even savable? I'm really upset here!!

responder: Howard Russell, Entomologist  Replied May 31, 2023, 11:28 AM EDT
response: Hello, Those are Viburnum leaf beetle larvae, Pyrrhalta viburni (Coleoptera: Chrysomelidae).  The shrub will likely survive if you spray now and again when the adults appear. The following is taken from a Cornell University Insect Diagnostic Laboratory Fact Sheet at http://www.entomology.cornell.edu/Extension/DiagnosticLab/IDLFS/VLBfactsheet2003.html Written by: Paul A. Weston, and E. Richard Hoebeke, Department of Entomology, Cornell University, and Brian C. Eshenaur, Cornell Cooperative Extension, Monroe County  The exotic beetle was first found in North America in 1947 in the Niagara Peninsula of Ontario, Canada. It was discovered in New York State in northern Cayuga County (Fair Haven Beach State Park) in July, 1996. Native plantings of arrowwood (Viburnum dentatum complex) in the park were found heavily damaged by larval feeding. Many of these shrubs were nearly totally defoliated, and only wisps of skeletonized leaves remained on the branches. The first North American breeding populations of this European leaf beetle were discovered in 1978 in the Ottawa/Hull region of Canada, where they were causing severe defoliation of ornamental viburnums, particularly the popular European cranberry bush viburnum (V. opulus).  The native range of P. viburni includes most of Europe. In North America this exotic leaf beetle is known to inhabit many areas of Ontario, the Canadian Maritime Provinces, and portions of Maine, New York, and, more recently, Pennsylvania, Vermont, and Ohio. In New York, surveys to date have detected its presence in at least 33 counties bordering the southern and eastern boundaries of Lake Ontario, along the eastern shore of Lake Erie, and along the northern tier bordering the St. Lawrence Seaway and Lake Champlain.  P. viburni adults are 4.5 to 6.5 mm long, the females being larger than the males. Their dorsal surface has small, dense punctures, and the space between punctures is somewhat rugose, or wrinkled, with thick, golden-grey pubescence. The head, thorax, and elytra (or wing covers) are generally brownish, but humeral angles, or shoulders, of the elytra are darker. Larvae of the viburnum leaf beetle are 10 to 11 mm 1ong when mature, slightly depressed and subcylindrical, and feed gregariously on viburnum foliage. Skeletonized leaves in the spring (May-June), heavily chewed leaves in the summer (July-September), and terminal twigs with characteristic egg "caps" arranged in straight rows, seen throughout the summer months, are characteristic of a viburnum leaf beetle infestation.  In Europe and North America, P. viburni overwinters in the egg stage. From late June to early July until October, females chew holes (1 x 1mm) in small branches or twigs of viburnum (generally the current year's growth, but occasionally in the previous year's growth) for oviposition. These egg sites -- deep, rounded cavities -- are often arranged in a straight row on the under surface of the terminal twig. Several eggs (average of five) are inserted into each cavity. In excavating each egg site, the female chews away the bark, splits the wood into small fibers that remain attached to the upper circumference of the area chewed away, and hollows out the egg cavity by excavating the pith. After filling the cavity with eggs, the female closes the opening by making a "cap" or lid composed of excrement, chewed bark, and cement from her collateral glands and pushing it up beneath the cluster of previously shredded wood fibers. For several weeks, the color contrast between the cap (brownish black) and the bark (green to brown) is sharp. This cap not only protects the eggs, but also sponges up and stores water that runs down the branch, thereby providing humidity for the eggs.  A female can lay up to 500 eggs. By early to mid-May of the following spring, the eggs hatch and the larvae feed gregariously on the underside of tender, newly expanding viburnum foliage. Larvae skeletonize viburnum foliage, usually starting with lower leaves and leaving only midribs and major veins intact. By early to mid-June, mature larvae drop to the ground, enter the soil, and pupate. By early July, adults emerge and begin to feed on viburnum foliage. Complete development from egg hatch to adult emergence generally takes 8 to 10 weeks. Adult feeding damage consists of irregular circular holes, and severe feeding can nearly defoliate shrubs once again. From summer through fall, adults will continue to be active, mating, laying eggs on terminal twigs, and feeding upon foliage until the first killing frosts. There is one generation annually.  This leaf beetle is restricted to feeding on species of Viburnum. It exhibits a strong preference for the popular arrowwood viburnums (V. dentatum complex), European cranberry bush viburnum (V. opulus), American cranberry bush viburnum (V. trilobum), and Rafinesque viburnum (V. rafinesquianum). Other viburnums also known to serve as hosts include Sargent viburnum (V. sargentii), wayfaringtree viburnum (V. lantana), nannyberry viburnum (V. lentago), and blackhaw viburnum (V. prunifolium). Particularly resistant species include Koreanspice viburnum (V. carlesii), Burkwood viburnum (V. burkwoodii), doublefile viburnum (V. plicatum var. tomentosum), Judd viburnum (V. × juddii), lantanaphyllum viburnum (V. × rhytidiophylloides), and leatherleaf viburnum (V. rhytidiophyllum).  Heavy infestations by viburnum leaf beetle can defoliate shrubs, cause dieback, and eventually kill plants. Valued plantings of the ever-popular European cranberry bush viburnum can be especially ravaged by larval and adult feeding. In addition to the heavy foliage damage caused by larvae and adults, even the inflorescences can be fed upon by larvae. Shrubs repeatedly defoliated over a period of two to three years are likely to die.  Pruning and destroying infested twigs after egg laying has ceased in the fall, anytime from October to April, is the most effective means of control for small scale plantings. When pruning is not practical, a number of pesticides may be effective in controlling this pest.  Homeowners and/or home gardeners may use carbaryl (sold as Sevin), cyfluthrin (sold as BioAdvanced Vegetable and Garden Spray) or bifenthrin (sold as Ortho Bug-B-Gon). Spray when larvae first appear in early May (75-100 GDD)* for best results. If damage from adults is excessive, a second application in mid-to late summer may be helpful.  Regards Howard.

responder: The Question Asker Replied May 31, 2023, 11:38 AM EDT
response: Thank you so much! It is in fact a cranberry viburnum but I fear it might be beyond hope however, I'll be getting the recommended spray today and going over it. It's unbelievable how quickly they've decimated it.Thank you again.On Wed, May 31, 2023, 11:28 AM Ask Extension <<personal data hidden>> wrote: