Viburnum Leaf Beetle on Snowball Bush: Insecticide Needed

The lacey, brown skeletonized leaves on your 20+ year snowball viburnum (Viburnum opulus 'Roseum') with tiny caterpillars/worms are classic viburnum leaf beetle (Pyrrhalta viburni) damage.

Life Cycle

• Eggs overwinter on twigs (visible as rows of capped holes).
• Larvae hatch in spring, skeletonize leaves (lacey appearance).
• Larvae pupate in soil, adults emerge summer, feed on leaves, lay eggs.

Control

1. Now (larvae active): Spray carbaryl (Sevin), spinosad, or bifenthrin. Dish soap does nothing—it's not an insecticide.
2. Fall/winter: Prune out and destroy egg-infested twigs (look for capped rows).
3. Next spring: Spray at first larval hatch (usually late April–May in Maine).

Recovery

Viburnums typically refoliate after spring defoliation. But repeated years weaken the plant. Consistent management breaks the cycle.

Diazinon is no longer sold for residential use—use current labeled alternatives.