The thin layer remaining turns clear or brown and the uneaten veins appear like a skeleton. The older larvae of the bristly roseslug and curled rose sawfly chew holes rather than skeletonizing the leaves. Roseslug and skeletonizing of leaf on right side of photograph. The curled rose sawfly also has one generation per year. The bristly roseslug has several generations throughout the summer.
Sawflies often feed on the undersides of leaves, so inspect all leaf surfaces.
Curled rose sawfly and leaf defoliation. Control Sawflies are best controlled when young. Several options exist for control. A physical tactic is to simply pick them off by hand. Dislodging them with a stick or a stream of water also works.