The viburnum leaf beetle (VLB), Pyrrhalta viburni, is an invasive insect that feeds exclusively on Viburnum species causing serious damage. VLB is native to Europe and was detected in Canada in 1947. The first report of VLB in the United States was in New York State in 1996. VLB is now found scattered across much of the Northeastern and Midwestern US.
Susceptible Hosts
Viburnum species, especially:
- Arrowwood viburnum (Viburnum dentatum)
- European cranberrybush viburnum (Viburnum opulus)
- American cranberrybush viburnum (Viburnum opulus var. americanum)
Signs of Damage
- In spring, holes in leaves which create a lace-like (i.e., skeletonized) pattern
- In summer, adults begin to feed, chewing oblong holes in leaves
- Severe infestations can cause complete defoliation of a viburnum shrub, which weakens the plant over time and can eventually lead to death.
Viburnum leaf beetle larva
Physical Appearance
- Adults are approximately ¼ inch long and yellowish-brown in color
- Larvae can be up to ⅓ inch long and range in color from yellowish green to light brown with a series of black spots and dashes on their bodies
- VLB larvae feed individually or in small groups and can cause significant damage to viburnum shrubs.
Viburnum leaf beetle adult
Biology / Lifecycle
- One generation per year.
- Overwinter as eggs and requires a chilling period of approximately five months, (Weston and Diaz 2005).
- Larvae typically appear in early to mid-May (80-120GDD) and feed for several weeks, passing through three instars as they grow.
- In early to mid-June, larvae pupate in the soil and adults emerge by late June or early July (1000+ GDD).
- VLB females lay eggs during the summer and into October (until 1st frost) by chewing small pits in twigs, deposit five to eight eggs into each pit, and then cover the pits with tiny pieces of chewed wood to protect the eggs.
- Each female can deposit up to 500 eggs.
- Eggs remain in place through the winter until they hatch the following spring.
Viburnum leaf beetle feeding damage
Treatment Strategy / Expectations
Viburnum leaf beetle populations vary in subsequent years. Therefore, monitoring is very important to determine pest pressure. Soil applied insecticides are very effective against this pest.
Cultural treatments (e.g., root collar excavation, proper irrigation, soil management, etc.) need to be considered to improve/maintain plant health.
| Product | App. Method | Dosage | Timing | Re-Treatment |
| Soil application Lower systemic bark spray | 1 packet/5-17 inches DBH, or 10-17 feet shrub height 6 packets/1 gal water apply 1.5-2.0 fl oz solution per 1 inch DBH | Larvae appear 80-120 GDD Adults appear in summer 1000+ GDD | Annual | |
| Soil application | 0.1-0.2 fl oz/inch DBH | Spring or fall | Annual | |
| Foliar application | 1.5 fl oz/100 gallons solution | Larvae appear 80-120 GDD Adults appear in summer 1000+ GDD | 2-week intervals during this period as needed | |
| Foliar application | 1-2 fl oz/100 gallons solution | Larvae appear 80-120 GDD Adults appear in summer 1000+ GDD | 21-day intervals during this period as needed | |
| Foliar application | 10.8-21.7 oz/100gal | Larvae appear 80-120 GDD Adults appear in summer 1000+ GDD | 4-week intervals during this period as needed. |
*Product is Rainbow Ecoscience’s industry standard recommendation for most industry situations.
Reach out to Rainbow Ecoscience Technical Support for additional protocol support.
Soil Application with HTI 2000
Always refer to product label for rates and approved uses. Some images courtesy of forestryimages.org or Wikimedia Commons. Use of the images does not imply endorsement of treatments.
