Probably sawfly larvae--tiny green "worms," usually feeding on the underside of the leaves, but sometimes seen along the edge of the leaf--though they are very hard to see until you get used to focusing in on them.

There is probably something you could spray on them, but I don't recommend that approach. In about 10 days, the beneficial bugs will arrive and gobble them up. In the meantime, make a quick early morning survey and pluck any you see on the undersides or along the edges of leaves into the grass. They probably won't find their way back to the rose. Or if you are up to it, squish 'em! (Which some gardeners enjoy with a vengeance!) : )

When such a simple remedy is available, I hate to resort to chemical means which can create all sorts of other problems while curing this one specific problem.

Kate

too many roses to be practical....I feel I will have to resort to chemicals...just to name of few...what are the 'other problems'?

Looks like Sawfly damage to me, as well and I agree that you should simply hand pick them and squish them, there is no reason to spray poisons when there is a simple completely harmless solution.

Gardenlady - "other problems" caused by spraying poison all over the garden include killing ALL of the beneficial bugs that eat sawfly larvae and other bad bugs, killing butterflies, killing bees, making pets & possibly children sick, etc. etc. One year early in my gardening life there was an infestation of whitefly in my garden. I bought a sprayer, and religiously went around spraying everything. That summer we had hardly any plums, pomegranites, or apples on the fruit trees, because I had killed all of the polinators!

Good bugs will show up soon and eat the sawfly larvae - In the meantime, if you don't want to spray them off with water, or hand pick them, just ignore them - that's what I do. My garden is full of butterflies, ladybugs, bees, and other wonderful things.

Jackie

The main problem with spraying poisons is that you cannot poison one thing without poisoning everything.

For example, many people spray for aphids when they could simply knock them off with a strong jet of water. Nature is a cycle of interconnected relationships. Killing off all of the aphids destroys the food source early in the season for beneficial bugs such as Lady bugs. Without this food source the Lady bug population suffers and declines. Later in the season when you need a healthy population of Lady bugs to feed on Thrips, there are not enough and you get a severe outbreak of Thrips. Spraying poison leads to the need to spray more poison, where is if you will let your yard get in balance you will have very few problems. I read about all of the problems people have with their roses and with gardening in general and many of the problems come from not understanding that nature is a web of interdependent cycles.

I have these sawfly larvae (rose slugs) in the roses every year, but they are never a big problem for me. I squish some and the paper wasps eat the rest.

However, if you have massive damage and want a chemical solution, Safer insecticidal soap will work, but you have to hit the worms directly. Otherwise the recommended insecticide is spinosad, a "reduced risk" pesticide that is relatively safe to handle and not very hard on beneficial insects. Aim at the undersides of leaves that have damage and those in the immediate vicinity, because eggs will not have been laid on all the roses. Avoid spraying flowers. A search for "spinosad" will turn up online sources.

Unless you have a perfect leaf phobia or exhibit, holes in leaves will not damage your rose bush. If you walk quickly past your roses or focus on the flowers, you'll not see the damage. The picture you posted doesn't show that much damage. It'd not bother me a bit.
I haven't sprayed an insecticide in 10 years. Damaging insects are soon eaten by birds and predatory insects. Before they'll arrive they have to have food available so you will have a certain amount of damage.
Insecticides kill caterpilars which eat leaves but turn into butterflies. My yard is filled with butterflies and bees.
A perfect garden doesn's show you're a great gardener, it shows you have little regard for the environment. Mom Nature has few perfect plants. She just has so many of them, the imperfections get lost in the crowd.

thanks to all for the lesson on good & bad guys! now...what a about BS, what is your favorite & BEST way of handling that issue?

I plant BS resistant roses. If it BSs badly, it's out of here, but so far have not had to SP any of mine. I lurked on the rose forums soaking up knowledge before I bought my first roses.

Have used safe less expensive than commercial insecticidal spray ~ Cornell Univ Formula ~ H2O, dish soap, Canola oil & soda solution, when sawfly larvae gets to be annoyingly much & defoliated my beautiful bush & made all the blossoms look like long legged beauties missing their pretty green skirts!!! Try it!

Has not affected the population of beautiful flying flowers in my piece of soil!!!

FWIW!!!