Rose Slug (Sawfly Larvae) Damage on New Shrub Rose

Identifying and Controlling Rose Slugs

A newly planted shrub rose tree shows white spots, holes in leaves, lost flowers, and only one bud remaining. Culprit: rose slugs (sawfly larvae).

Life Cycle

Female sawflies lay eggs in leaf margins. Larvae hatch, feed on leaf undersides (creating windowpane spots then holes), drop to soil to pupate, emerge as sawflies. They resemble caterpillars but are primitive wasp larvae.

Control

• For light infestation: remove affected leaves, squash larvae.
• For heavy infestation: spray thoroughly on both leaf sides with insecticidal soap, neem oil, or horticultural oil. These smother larvae; most chemical insecticides fail.
• Spray soil around base—pupae overwinter there.
• Safer's Insecticidal Soap is effective.

Timing

Early intervention prevents escalating damage as larvae grow. Monitor weekly through season.