Question: what is eating the leaves on my knockout roses?
Answer: Rose Slugs The rose slug is actually not a slug. It is larvae of sawflies, which lay their eggs on the underside of rose leaves. These annoying pests feed on the leaves of Knock Out roses, leaving holes in them. ... Spraying the infested shrub with ready-to-use insecticidal soap weekly or biweekly helps control rose slugs.