Thysanoptera, infamously known as Thrips

Thrips or thysanoptera are insects measuring between one and four millimeters. Brown as larvae, they can be recognized as adults by their fringed or eyelashed wings. These predators feed on leaves and flower buds.

There are several thousand species of Thysanoptera. Those that occur in France mostly belong to the suborder Terebrants and the family Thripidae. Among the most widespread are :

The Californian thrips Frankliniella occidentalis ;
Pea thrips, Frankliniella robusta;
Tobacco and onion thrips, Frankliniella tabaci.

Thysanoptera attack all plants. Trees, vegetables, indoor plants and flowers can all fall victim to a thrips invasion.

But thysanoptera aren't just pests! Some species act as pollinators.

Contributing factors

Thrips like heat and humidity. Greenhouses and indoor plants are therefore their favorite targets.

The wind, your clothes, your hands or unsanitized gardening tools all contribute to the spread of the parasite.

How it works

Thysanoptera attack plants by perforating their cells and digging very long galleries. They feed on sap, nectar and pollen.

Thrips reproduce rapidly. Several generations can infest the same plant.

Symptoms

A plant attacked by thrips is strewn with silver spots. Its growth is slowed down, its young shoots are deformed, its flowers wither faster and it becomes necrotic.

Thysanoptera rarely cause plant death. But they do spread diseases that can be fatal, such as galls and virosis.

Treatment

Preventive measures

Keep an eye on your crops to make sure they haven't been invaded by thysanopterans. Before introducing a new plant, check that it is not contaminated. To do this, observe the underside of leaves or stems. Thrips tend to gather there in clusters.

Remember to wash your hands and tools when gardening. This will reduce the risk of contamination.

Curative measures

Thysanoptera fear water. You can repel them by regularly watering the underside of foliage or the base of plants.

When thrips have set their sights on potted plants, start by showering the plants with a spray strong enough to unhook the insects. Then replant in new substrate and a disinfected pot. Quarantine the specimens in a cool room until you're sure the danger has passed.

For outdoor plants, try chromatic traps. Thrips are attracted by the color blue. Use a blue sticky trap to catch thrips.

If you're a fan of natural solutions, prepare an insecticide based on black soap and garlic decoction. Spray this mixture two or three times a day, every five days, until the parasites are eliminated.

Too heavy an infestation? Turn to commercial chemical insecticides.