Knowledgebase
Garden pest #871629
Asked June 04, 2024, 10:35 PM EDT
Anoka County Minnesota
Expert Response
https://apps.extension.umn.edu/garden/diagnose/plant/annualperennial/roses/
From your description, perhaps a rose slug, a kind of sawfly larva. If so, insecticidal soap should be effective:
https://extension.umn.edu/yard-and-garden-insects/sawflies