Viburnum leaf beetle
Pyrrhalta viburni
33 host plants
Last updated
This profile synthesizes data from multiple published sources. Expert field review is in progress.
Viburnum leaf beetle larvae skeletonize leaves in May and June, leaving only the upper leaf surface intact and creating a lacy appearance. Later, adults chew irregular holes in summer foliage (July to September). You will see small black egg-filled pits in viburnum twigs in fall. This invasive beetle has been documented in northern regions of the Pacific Northwest.
Prune and destroy infested twigs in late fall when eggs are visible as black caps on branches. Severe infestations warrant removal of entire branches or even plants if spread to new areas. For new infestations, contact your county extension office. Parasitoid wasps and predatory beetles provide natural control over time. Do not use broad-spectrum pesticides.
Quick Reference
Viburnum leaf beetle First egg hatch typically begins around 1085 GDD₃₂. As of April 23, 2026, all seven Puget Sound stations have passed this threshold (1434.4–1592.7 GDD₃₂), so First egg hatch is likely underway across the lowlands.
Regional Season Tracker
GDD₃₂ accumulation across 7 Puget Sound stations · as of Apr 23, 2026| Station | GDD₃₂ | Current Stage | Next | To Go |
|---|---|---|---|---|
| Issaquah / East King | 1,593 | First egg hatch | — | — |
| Seattle / UW | 1,554 | First egg hatch | — | — |
| Kent / Auburn | 1,537 | First egg hatch | — | — |
| Olympia / Tumwater | 1,505 | First egg hatch | — | — |
| Bellingham / Whatcom | 1,483 | First egg hatch | — | — |
| Tacoma / Puyallup | 1,472 | First egg hatch | — | — |
| Sequim / Rain Shadow | 1,434 | First egg hatch | — | — |
Source: UMD IPMnet catalog. Sources: UMD: extension.umd.edu; Cornell: blogs.cornell.edu. About GDD₃₂ →
Young larvae skeletonize leaf undersides between veins. Mature larvae create small holes. Adults produce oblong feeding marks. Severe infestations leave only midribs and veins, causing complete defoliation. Repeated defoliation causes branch dieback and plant death.
Cultural Controls
- Winter pruning: remove egg-scarred terminal twigs (distinctive rows of dark pit marks covered with frass) during dormancy. This is the most effective single control measure.
- Sticky barrier or V-shaped tape collar around trunk base to intercept larvae descending to pupate in soil. Larvae crawl down rather than drop.
- Hand-pick adults and larvae during active feeding.
- Plant resistant species: V. plicatum var. tomentosum, V. carlesii, V. burkwoodii, V. davidii, V. rhytidophyllum. Avoid highly susceptible species (V. dentatum, V. opulus) in areas with known VLB populations.
First WA specimens found in Whatcom County (early 2000s, shortly after 2001 BC detection). By 2015 gardeners were removing viburnums killed by VLB. Invasive from Europe, spreading through WA. Native V. edule and V. ellipticum at risk.