There are lots of ideas out there for controlling thrips. Probably the simplest is to put a teaspoon of Dawn or other dishwashing detergent in a spray bottle, then painstakingly spray all the blossoms in the garden and parts of the plants near them. Not 100% confident this would kill them all, but it should help a lot. You might also prune off all the infected blossoms and discard them far from your roses, they will never quite please, and doing so could carry away thrips that weren't reached by this treatment.
Lady beetles I am told eat thrips, but in my experience by the time there are enough lady beetles in the garden, thrips have done there damage and gone.
Neem oil works, too, but I understand that it kills bees and other beneficial insects. My guess is that any horticultural oil would work. Or even vegetable oil. You could also dust each rose bud with rotenone as it forms, but this would be painstaking work, I suppose.I would guess that soapy water might be as least as effective and a little easier to work with.
