Might be a sawfly (rose slug) or maybe some type of caterpillar.

http://www.weidners.com/Roseslug.htm

http://www.rose-roses.com/problems/badinsects.html

If it is rose slugs, I have successfully used safers insecticide soap.
Maybe others can recommend something else.

Look at the very first image and read the first entry that goes along with it. That's probably your problem.

Thank you! I'll work on spraying the underside of the leaves.

I just finished a three-day plant sale in Richmond, and no fewer than 5 people came to me find a solution to this very same problem. One woman even had photos on her Iphone (photo attached below) No one could find the culprit on their roses.

{{gwi:249878}}

I'm convinced that it's some sort of sawfly larvae at work eating leaves. Some of the damage in the woman't photos looked to be caused by larger larvae, and they're probably busy pupating right now. That would be why no one could find them.

I have had a few rose slugs in the greenhouse, but none outdoors yet to speak of. Perhaps the plague is coming.

Connie

Rose slugs blend right in and are hard to see. Here they do most of there damage at night.

Connie - you weren't at the Maymont plant sale, were you? I was there and hoped to see you.

I didn't do Maymont ... I was at Ginter instead.

As I predicted above, the plague has arrived in my potted roses. I mashed a juicy rose slug yesterday, and his brethren have been having a feast on my leaves. Grrrr. I need to go out at night with my flashlight to make sure that this is the only problem I have. As Jim said, many leaf-eating varmints are nocturnal.

Connie

If you dont have too many roses, the easiest thing to do is pick them off and throw them like a baseball, good and far away. Just go thru quickly all the undersides, and pull them off. The edges seeing from the top are easy to see if a rose slug is chowing down along the edges.

On Sunday I saw an adult sawfly on one of the roses near my townhouse. I tried to crush it but it flew off too quickly.

I know a rose that will have rose slugs on it soon................. :(

New York Rose,

Would something like insecticide soap smother the eggs if applied? Or are eggs well protected?
I've never seen a sawfly or eggs, but,have encountered the larvea stage (rose slugs) on the bushes.
Here's what confuses me, I hear everyone talking about Rose slugs being found only on the underside of leaves.
The critters here were on the tops, bottoms, and on the canes. Maybe I actually had caterpillars. If they return this season, i'll take a really good close-up pic and a sample of a few and ask Penn State exactly what they are.
I opened one website that had pics of rose slugs and what I had here matched perfectly, they could of been twins. lol

Rose slugs are the larvae of rose sawflies. They bear a resemblance to caterpillars, but when you learn enough about insects (btw, this is not necessary to be a successful gardener, including successfully growing roses), you will learn that there are external, identifiable differences between the larvae of sawflies (including rose slugs), and the larvae of moths & butterflies (aka "caterpillars").

{{gwi:249876}} This is a picture of a European species. It isn't the rose sawfly I saw (the one I saw was completely black), but there is more than species known by the name "rose sawfly". These insects are small (roughly 1/8" long) and bear a resemblance to wasps (which are in the same insect order as the sawflies), but sawflies have no stingers. Wasps feed on a variety of foods, and often are predators of other insects, but immature sawflies always eat plants. Sawflies are unable to cause physical harm to humans, but their babies may eat your trees & shrubs.

I think if I had a large enough number of rose slugs in my garden I wouldn't be surprised to see them eating on the tops of the leaves, but I would expect to see a larger number of them below the leaves than above the leaves.

I also know the difference between how caterpillars and rose slugs look, so if you know how to do it you could post your picture here. I'd be very willing to take a look at your picture(s) to see if I could give you an answer as to whether you're dealing with a sawfly ("rose slug") or a moth ("caterpillar").

Just give me some sort of a "heads-up" so I know that you've posted something for me to look at.