Thrips are very small, slender insects with mouthparts specialised for sucking and rasping. Adults are 1-2 mm long, and most have a pair of narrow wings fringed with long hairs. Juveniles are wingless and often paler or lighter coloured than the adults.
Some species feed on insects and mites, and can therefore be important biological control agents, but thrips are better known as pests due to the damage that plant-feeding species cause in crops. Thrips attack a wide range of crops including vegetables, fruit trees and ornamental plants.
Thrips cause direct feeding damage when they pierce plant cells and feed on the contents. When they feed on leaves, this produces characteristic leaf ‘silvering’ and their dark droppings can usually be seen around the sites where they have fed. When they feed on fruit (such as strawberries), they drain the pigment from the cells, stripping the fruit of its colour. Thrips also feed on growing tips, buds and emerging flowers, leading to distortion of fruit and leaves, and unsightly scaring and discolouration of flower petals. Some species of thrips also transmit plant diseases.
Significant pest species include:
- Western flower thrips (Frankliniella occidentalis)
- Plague thrips (Thrips imaginis)
- Tomato thrips (Frankliniella schultzei)
- Onion thrips (Thrips tabaci)
- Greenhouse thrips (Heliothrips haemorrhoidalis)
A variety of natural enemies, including predatory mites, predatory bugs, predatory thrips, lacewings, ladybirds and parasitoid wasps, can all contribute to the control of thrips, and it is possible to achieve good results without necessarily resorting to chemical treatments.
Montdorensis predatory mites feed on both thrips and whitefly, and they are proving to be a very effective biological control agent for these pests in protected crops.
Orius predatory bugs feed on both adult and juvenile thrips. They require pollen as part of their diet so they are best applied in crops where pollen is naturally abundant (e.g. capsicum, eggplant, strawberry, raspberry and gerbera).
Hypoaspis are soil-dwelling predatory mites that feed on thrips when they drop to the ground to pupate. They complement the activity of Montdorensis and Orius in a thrips management program.
Optiroll Super Blue sticky rolls are specially designed to maximise the capture of thrips. Use ribbon to encircle the perimeter of the growing area or place ribbon along crop rows to mass-trap flying insects. This product is ideal for large area trapping.
Optiroll Super Yellow sticky rolls are designed to maximise the capture of flying insects such as whiteflies and thrips. Use ribbon to encircle the perimeter of the growing area or place ribbon along crop rows to mass-trap flying insects. This product is ideal for large area trapping.
Blue sticky traps are a useful tool for monitoring populations of adult thrips. This shade of blue is especially attractive to thrips.
Yellow sticky traps are a useful tool for monitoring populations of adult thrips and other flying insects.
ThriPher pheromone lures contain a species-specific aggregation pheromone for Western flower thrips (Frankliniella occidentalis). They can be used in combination with blue (or yellow) sticky rolls to maximise the capture of this damaging pest species.