Avid rose gardeners know about the perils that can befall the objects of their affection. Caterpillars that like to feed on rose leaves are among these dangers. If you suspect that caterpillars are damaging your roses, follow this procedure to confirm or deny your suspicion.
Look for a green worm on your rose petals. The tobacco budworm is green and feeds on rose petals rather than leaves.
Check for rolled leaflets, which indicates that a leaf rolling caterpillar has been around your roses.
Watch for a small green caterpillar with orange spikes. If you see one, you have the spiny oak slug on your hands.
Look out for the stinging rose caterpillar. The caterpillar is smaller than 2.2 cm (7/8 inch) and mostly yellow. You will also notice long, smaller spines and a wide purple band on this caterpillar.
Check for rose slugs. These caterpillars look like green snails and can be found under the rose bush's leaves.