Sawfly Larvae
Rose sawfly larvae are often called rose slugs. They are not slugs and they are not caterpillars, even when they look caterpillar-like. This matters because some caterpillar products are not useful against sawflies.
Signs
- Windowpane feeding where leaf surface is scraped but veins remain.
- Skeletonised leaves when feeding is heavier.
- Green larvae on leaf undersides, sometimes matching the leaf colour well.
- Damage can appear suddenly in spring or early summer depending on species and region.
Look-alikes
- Caterpillars can chew larger holes but are a different insect group.
- Japanese beetles skeletonise leaves and flowers but adult beetles are visible during the day.
- Leaf-cutter bees remove neat rounded pieces from leaf edges and usually do not need control.
Controls
- Inspect undersides of leaves.
- Squish or handpick small numbers.
- Prune off a few badly damaged leaflets if it helps remove larvae.
- A firm water spray can dislodge light infestations.
- Insecticidal soap or horticultural oil may help when it directly contacts larvae and the product is labelled for the use.
Direct treatment cautions
- Bacillus thuringiensis kurstaki products target caterpillars and should not be expected to control sawfly larvae.
- Avoid unnecessary broad-spectrum sprays because they harm beneficial insects.
- Follow current local labels and UK/EU authorisations before any pesticide use.
Use controls lawfully: Current local product label/register wins for any pesticide, fertiliser, or soil amendment use.
Sources
Discussion log
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