Plant Problem Diagnostic
What's Eating My Rose Leaves?
The short answer
If your rose leaves are skeletonized — grazed down to a thin, translucent 'windowpane' layer with the veins left behind — the likely culprit is the roseslug, the larva of a rose sawfly. They are small, greenish, caterpillar-like, and feed on the undersides of leaves, which is why they are easy to miss.
That damage differs from Japanese beetles, which chew all the way through the leaf and leave a lacy, holed skeleton (and are large, metallic, and feed in daylight). For roseslugs, check leaf undersides in mid-to-late spring; a strong hose spray or hand-removal handles small numbers, and horticultural oil or insecticidal soap sprayed on the undersides helps larger infestations.
Identifying roseslug damage
Roseslugs first appear in mid-to-late spring. Young larvae rasp the leaf surface, leaving windowpane patches; heavier feeding leaves leaves brown and dry.
They are sawfly larvae, not true slugs and not caterpillars, so products aimed at caterpillars (Bt) do not control them. Look on the undersides of leaves for the greenish, slug-like larvae.
Telling it apart from Japanese beetles
Roseslugs skeletonize — they remove the soft tissue and leave the vein network and a papery film. Japanese beetles chew through the whole leaf, producing holes and a lace-like remnant, and the adults are large and metallic green-bronze.
If you see the beetles themselves clustered on flowers and foliage in summer, treat it as a beetle problem instead.
What to do
For light infestations, knock larvae off with a strong stream of water directed at the leaf undersides, or remove them by hand.
For heavier infestations, Extension guidance points to insecticidal soap or horticultural oil, which require direct contact — spray the undersides where the larvae feed. Early detection widens your options, so scout roses through spring.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- University of Delaware Cooperative Extension — Roseslug Sawfly — Roseslug is a sawfly larva that feeds on leaf undersides and skeletonizes rose leaves, leaving windowpane damage; hose spray, hand removal, oils or insecticidal soap control it.
- NC State Extension — Roseslug or Rose Sawfly — Roseslugs skeletonize leaves leaving veins intact; larvae look caterpillar-like but are sawflies; direct-contact sprays to leaf undersides needed.