Thrips, Heliothrips haemorrhoidalis and Taeniothrips simplex. Both field and greenhouse plants are attacked by thrips. Flower buds and flowers are attacked by the gladiolus thrips, T. simplex. A few species of thrips are severely injurious, with the gladiolus thrips being the worst offender. The flower buds may be injured so that no good blossoms result.
Females lay eggs in slits made in leaf surfaces.
The nymphs take from 2 to 4 weeks to mature, allowing several generations in one year. They overwinter in the corms. Storing the corms at 40 - 45 F can break the life cycle. Another method is to make a solution of 1.25 tablespoons of disinfectant per gallon of water, and soak them three hours in this solution just prior to planting. The tiny insects hide in the sheaths of the flower stem where it is difficult to reach them with a spray.