Close-up of roseslug sawfly larva.

Roseslug sawfly damage called ‘window-paning’.  The leaf epidermis becomes ‘frosted’ as leaf dries out from feeding on underside of leaf.

‘Window-paning’ damage on Knock-out Roses caused by roseslug sawflies.

Underside of rose leaf with damage caused by roseslug sawfly.  Larva is feeding on leaf.  All photos provided by Brian Kunkel, University of Delaware