Gladiolus Thrips
Gladiolus thrips (Thrips simplex) is a tiny, slender insect that ranks as the most damaging pest of gladiolus worldwide. Gardeners in upstate New York need to take it seriously because it does not just attack plants in the ground — it travels with the corms, surviving storage conditions that would kill most insects, and reinfests new plantings the following season.
Adults and nymphs feed by piercing plant tissue and extracting cell contents. On gladiolus, this produces a characteristic silvery or white streaking on leaves and sheaths, distorted and discolored flowers, and brown, corky lesions on corm surfaces. Populations build quickly in warm, dry summers. The pest also attacks lilies, irises, and freesias, so mixed bulb plantings carry higher risk. Infested corms dug in fall can harbor hundreds of individuals sheltering beneath the outer husks.
Because the insect overwinters inside stored corms rather than in garden soil, corm sanitation at digging time is the most important management step. Treating corms before storage breaks the cycle and protects next year's planting.
Foliar and corm pest of gladiolus and related bulb crops, causing direct feeding damage to leaves, flowers, and storage organs.
Silvery or whitish streaking on leaves, brown flecking, and flowers that fail to open or appear deformed and discolored. Severe infestations leave corms with rough brown patches.
Remove and destroy affected blooms. Inspect corms before storage and discard damaged ones. Store corms cool and dust with an appropriate insecticide. Spray plants with insecticidal soap or spinosad during active growth if thrips appear.