The larvae find their way to the tip of the bulb and then go downward into the interior. They pupate in August in the bulb or in the soil near it. Certain larvae overwinter in the bulbs, but these are thought to be the second generation, from which flies emerge the following spring. Destroy any infested bulbs after harvesting. Onion thrips, Thrips tabaci .
Thrips are very small insects with narrow fringed wings that are lacking in the nymphs.
In feeding, a thrips leaves a whitish chain-like mark on the surface. They hide in the sheaths of the leaves and are difficult to reach with an insecticide. Hot, dry weather increases thrips damage.