Thrips
Thrips, also known as aerial plakton because of their poor flight characteristics, should be eradicated immediately. The infestation can be recognized by silver-bright spots on the upper side of the leaves. If the plants are heavily infested, the leaves are crippled, the leaves fall and turn yellow. Unshapely buds that sometimes do not open and fall off, dry out or rot are also signs of infestation.
Natural enemies such as predatory bugs, ladybugs, spiders and ants, as well as a number of other flies and wasps, help to contain the infestation if it is not too severe.