Western flower thrips is found in highest numbers in flowers and on young growths of plants. The adult and larvae tend to hide in flowers or in crevices on the plant, which makes them difficult to reach with pesticides. The thrips can damage plants in two ways, direct damage from feeding and by transmitting plant-damaging viruses. The adults and larvae have short rasping mouth parts and feed by puncturing the surface cells of plants, sucking out the cell contents and killing the plant tissue. Thrips feeding can cause distortion of young leaves and fruit, spotting on flowers and formation of pale often yellow areas on leaves.
Older leaves can develop a silver sheen.
Areas where thrips have been feeding are covered with characteristic black specks. These are their faeces. Cucumber leaves damaged by thrips. Note the pale-coloured areas are where thrips have been feeding and the tiny black specks of their faeces. Thrips damage to cucumber leaves.