Thrips

Thrips are minute, slender-bodied insects, most only 1-2 mm long as adults, ranging from pale yellow through brown to black depending on species. Adults have narrow fringed wings held flat over the body and are elongated and cigar-shaped when viewed from above. They move quickly when disturbed and often shelter deep in flowers, unopened buds, leaf axils or curled new growth. Juvenile stages (larvae/nymphs) are wingless, pale cream to yellow, and similarly slender but smaller, feeding alongside adults on the same tender tissue before dropping to the soil or leaf litter to pupate.

Thysanoptera is a large insect order and Australia hosts many species affecting ornamentals, turf, fruit, vegetables and nursery stock, including western flower thrips, onion thrips, plague thrips, greenhouse thrips and citrus thrips. Different species favour different hosts and plant parts, but all feed by rasping the plant surface and sucking up the released sap.

Thrips are active year-round in warmer regions and become most prolific in spring and summer when conditions are warm and dry. Populations build rapidly on new flush growth, in flowers and in protected cropping or nursery environments where wind and rain do not knock numbers back. Many species also move in from surrounding pasture, weeds or crops when those dry off or are cut, so activity can spike after mowing or harvest nearby.

Management relies on regular monitoring of susceptible growth stages, removing spent flowers and weedy hosts, encouraging predatory mites, lacewings and pirate bugs, and maintaining even plant vigour since stressed, water-affected growth is more attractive to feeding. Some thrips species also vector plant viruses such as tomato spotted wilt virus, making early detection important in nursery and vegetable production.