Have viburnums? If so, it is time to scout your plants. The Viburnum Leaf Beetle (VLB) is voracious, insatiable and will treat your shrubs like an “all you can eat” salad bar. The eggs have hatched and the larvae are currently feeding on the undersides of foliage, defoliating between the midrib and larger veins. The larvae vary in color; however, all have black spots along their sides and a row of black dashes running the length of their backs. They are usually found feeding in groups.
By mid-June the larvae will make their way to the ground to pupate and emerge as adults in early July. VLB adults pick up where they left off as larvae and continue to feed on the viburnum foliage. Adult beetles remain active until the first frost. VLB is the only known pest to skeletonize viburnum leaves. Heavy and repeated infestations will defoliate shrubs, causing die-back and eventually killing the plant.
A relatively new pest to our area, VLB was first confirmed in Cook County in 2009. In 2012, it was reported to be found in DuPage County. Last year, several reports of severe defoliation were reported in both DuPage and Cook County. This pest is native to Europe and was brought to North America on infected viburnums.
Early detection is important. At this point in the season, pesticide applications are the best option for controlling VLB. If you suspect this hungry pest is on your property, call KTS and our ISA Certified Arborists can provide you with proper recommendations.
The links below offer further information on Viburnum Leaf Beetle, including great pictures of the pest. In addition, the information offers a list of viburnum species most susceptible and most resistant to VLB.
http://www.mortonarb.org/files/GDD_May_22_2015.pdf
http://www.mortonarb.org/files/Plant_Health_Care_Report_2014_5.pdf