They seem to be attracted to light-colored blossoms. To discourage thrips from attacking, spray plants with a systemic insecticide just before the buds open. If signs of thrip damage appear, remove and destroy infected flowers and buds. Spray infected plants with an insecticide. If the infestation is severe, repeat applications may be necessary.
Roses fail to blossom or existing buds suddenly turn black and die.
The foliage and the stem surrounding affected buds may also blacken and die. The larvae feed in clusters at the bases of rosebuds. Prune off and destroy all infested plant parts. Spray plants with an secticide and apply a systemic insecticide to the ground around the plants where the larvae pupate. Holes appear in flowers and then in leaves.