They can certainly vector disease (like viruses) from plant to plant.

No.... They are just little sucking things. They are not the same as the mite that is the host for Rose Rosette Virus. Ignore them or continue to blast with water. Or wait for ladybugs. :-)

Don't worry, be happy! If they bother you you can get out a hose and wash them off with a hard stream of water. Or, you can brush them off with your hands. If you wait a bit, ladybugs and other good bugs (assuming you do not use pesticides) will come and eat them! Also there is a darling tiny bird here who shows up in large flocks and eats them.

Jackie

No, I don't spray any kind of pesticides. Haven't seen any little birds except on our bird feeders and no other beneficial insects yet. I just sprayed the bushes with water when I watered this morning and instant clean bushes!

I guess I didn't have aphids last year (which was my first). This year I had to go get my glasses to figure out why my first bud of the season looked bad. Originally, I thought it had some left over frost damage, but SURPRISE!

I find the wipe them off with your fingers method the most effective for a heavy infestation. But if they're really bad and you don't want to do that you can use a spritz bottle with a little drop of dish soap and filled with water and spray them. The soap dries them up and then you can rinse them off with the hose. What ever you do you will have to do it repeatedly to get all the succeeding hatches too.

I find that the first season I plant roses in a new area I get every bug in the area. But by the next season all the good guys discover the bug feast and my problems are pretty well gone.

I love the tiny birds, they perch on the neck of a bud and feast away

We have some of those small finch-like birds too. I have found that having the fountain attracts more (for the water). I had quite a few aphids in early march, but after a ladybug application (and a few generations of larvae) the aphids are under control. We also have a nice species of syrphid fly that has little green worm-like larvae that eat aphids.

I've occasionally seen little green worms on the underside of rose leaves. I'm afraid I've been squashing them, but I wonder if these are the aphid eaters that lorrihz mentions. I'll leave them alone from now on.

If they're on the underside edges of leaves they might also be rose sawfly larvae, don't know what the local name is, but they're a pest. I have the kind locally that lay their eggs into the cane, and they are a tremendous nuisance. The caterpillars are ok, although left unchecked they can defoliate a small bush, but I can mostly let the bluetits and finches deal with them. Generally, I find that bugs that appear in multiples are pests and bugs that appear as singletons are predators.