Rose Slugworm (Sawfly Larvae) Damage: Skeletonized Leaves on Standard Roses

Identifying and Treating Rose Slugworm in Northeast England

A potted standard rose (likely floribunda) with yellow, fragrant flowers develops skeletal leaves—only veins remain—4-6 weeks after new growth. Gardener in northeast England asks if insect or fungus.

Diagnosis: Rose Slugworm (Sawfly Larvae)

Tiny slug-like creatures eat leaf tissue between veins, leaving "skeletons." They feed on leaf undersides, making contact sprays ineffective. Common in cool, wet climates like coastal Canada and northeast England.

Effective Treatment

• Systemic insecticide: Absorbed by plant, kills larvae when they feed
• Contact sprays fail because pests hide under leaves
• Apply at first sign of damage in spring

Climate Context

Cool, wet springs and mild summers favor slugworm populations. Vigilance in May-June prevents severe defoliation.