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What is it?

One of the most common pests, both adult and immature thrips, of gladiolus plants.

What does it look like?

Flowers and foliage will have silvery white streaks. Discoloration and deformity may occur in the flowers. Blackish brown insects with slender wings can be seen on the foliage in early morning and late afternoon on overcast days. On sunny days, the thrips hide in flower buds and between leaves. Corms may become infested and turn brown and corky, or fail to grow.

How does it manifest?

Immature and adult thrips feed on plant tissue. The injured tissue then turns silvery white. Adult female thrips insert their eggs into the broken plant tissue, and young emerge within two to four weeks to actively feed. Feeding season is from spring until the first frost in the fall. Thrips will reproduce continually during this time. They cannot survive freezing temperatures. In warm-winter climates the adult thrips hibernate in the soil. In cold-winter climates they hibernate in the plant corms.

What can you do about it?

When you notice the signs of thrip infected plants, spray plants with an insecticide containing diazinon or acephate. If reinfestation occurs, spray again every ten days until they have died off and you have destroyed all the eggs. Before storing corms, check for brown ones and discard. To prevent further corm infestation in your storage area, dust them with an insecticide containing malathion.