It was more of a problem for fragrant roses than for roses with no fragrance. It was more of a problem for early blossoms - ones that occurred before thrips predators were well established in the garden for the season - than for later ones. It was more of a problem for roses with thin petals than for roses with thicker petals. By now very few new blossoms show damage.
I tried the blue stickies recommended elsewhere and I cannot say I found them to help much. The labels suggested that they are for "monitoring populations" of thrips. I will not use systemic insecticides of hundreds of roses, since I have no info on how this will affect the local population of thrip and aphid predators. So I'm resigned to losing a large number of early blossoms to this sort of thing. This means more work, as I will have to water my roses more to stretch out blooming season...
My cunning plan for next year - if I can remember - is to try dusting the buds of the most desireable roses (to thrips and aphids) with pyrethrum or with diatomaceous earth.
