What are the damage symptoms of thrips in carnation?

Thrips are damaging to carnation flowers in dry summer months. On coloured flowers they cause white flecks, but on white flowers they cause tan to brown specks. The western flower thrip, Frankliniella occidentalis, is the most prevalent thrip in Hawaii-grown carnations. Other species- e.g., Thrips palmi, T. tabaci, and T. hawaiiensis- are also common. The western flower thrip and T. palmi are the most difficult to control because they have developed resistance to insecticides. Adult western flower thrips, are about 1/20 inch long and are tan; the young are yellowish.