Spinosad is effective but would need sprayed at least once per month... Top and undersides of leaves need sprayed along with canes etc...Overall spraying...Please follow directions as Spinosad can be harmful to bees if sprayed at the wrong times...

Or you could pick them off the underside of leaves etc. or try spraying them off with a water hose...

You have Rose slugs (Sawfly Larvae) which are tiny green worms usually found underneath leaves....What you seen is what's eating your leaves! (Rose slugs can range from small to 1 inch long...)

Thank you so much! Any tips on spraying them with water? Would you just spray with the jet setting on the hose (most powerful spray) and try to get the underside of the leaves? Since they're so thorny I think it might be tricky to pick them off, esp because I have so many rose plants.

By the way, I noticed that some of the bugs are tiny and green and some are black. Are they both rose slugs? Thanks!

Never seen a black rose slug I think there all greenish in color..

I would not spray water to hard because it could injury your rose bush...Gentle but effective spray if that makes sense...lol

In agreement with Jim. That the damage to your rose leaves are from rose slugs and that they are all a greenish color. Rose slugs are not true slugs.Thats is why none of the slug products will work. I read that they were nicknamed slugs because they secrete a slimy substance that gives them a slug like appearance. There are insects that eat them but if none are around they sure can make a mess out of your leaves.

Hmm, that's a good point about other bugs killing them off. Our neighbors don't seem to have these problems with their roses, but my husband did hire a pest service for our house that sprays a substance called Bifenthrin and uses Essentria® G Granules. Could those be killing off the good predators?