In a nutshell, thrips are a generalist pest found on many different types of plants, roughly 0.5-14mm long, depending on species. They have 6 stages: the egg, two larval instars, a pre-pupa, a pupal instar and the adult form. In Canada we see the Western Flower Thrips (Frankiniella occidentalis), Onion Thrips (Thrips tabaci), the European Flower Thrips (Frankiniella intonsa) and the Echinothrips (Echinothrips americanus).
Thrips cause damage to plants by piercing the cells of the surface tissues and sucking out their contents, causing the surrounding tissue to die. The resulting silver-grey patches on leaves and the black dots of their excreta indicate their presence in the crop. The vigour of the plant is reduced by loss of chlorophyll. When infestations become serious the leaves themselves can shrivel. They are also one of the primary vectors of plant viruses.