Viburnum beetle

What it is

Viburnum beetle is a native leaf beetle that feeds only on viburnums. Laurustinus, the guelder rose and the wayfaring tree are commonly attacked, while some thick-leaved species are rarely touched. Healthy shrubs usually recover, but repeated attacks weaken them and look unsightly for much of the year.

Symptoms

From late April, creamy yellow larvae with dark markings, up to about 8 mm long, feed on the undersides of young leaves, eating between the veins so leaves look lacy or skeletonised. Damaged areas turn brown. Later in summer, greyish brown adult beetles about 5 mm long chew rounded holes in the leaves. Caterpillar damage is usually more ragged and comes with visible droppings.

Cause

Females lay eggs in small pits chewed into the tips of young twigs in late summer and autumn, sealing each with a cap of chewed bark and droppings. The eggs overwinter and hatch as leaves open in spring. Larvae feed for several weeks, drop into the soil to pupate, and the adults emerge in midsummer.

Control

From late April, check the undersides of leaves and pick off or squash larvae, or shake branches over a sheet and dispose of what falls. In winter, look along the tips of last year's shoots for rows of small raised scars and prune out those twigs, binning or burning them. Damaged shrubs respond well to feeding and mulching. Insecticide is a last resort and best avoided on plants flowering for pollinators; if used, follow the label.

Prevention

Inspect new viburnums before planting. Encourage birds, ladybirds and lacewings, which take larvae. If beetles are a persistent problem, grow less susceptible types such as Viburnum carlesii or Viburnum rhytidophyllum rather than more laurustinus.

Plants often affected

• Laurustinus

Could it be something else?

These problems share some of the same symptoms. Compare them, or run the symptom checker with these signs ticked.

• Box tree caterpillar
• Leek moth
• Rosemary beetle
• Cabbage caterpillars

Months to keep an eye out: April, May, June, July, August and September.

Sources

Identification and life-cycle details were checked against the references below. Text and advice are our own. See our editorial policy.

• Wikipedia — Pyrrhalta viburni
• Cornell University — Viburnum leaf beetle