The black tea thrips, Heliothrips haemorrhoidalis, is widely distributed in the tropics and subtropics; it also occurs in greenhouses of temperate areas, is highly polyphagous, and has been recorded from more than 100 plant species. Seriously damaged crops include tea, citrus, avocado, as well as cyclamen and many other ornamentals.
Life cycle and appearance of Black tea thrips
Adult black tea thrips are dark brown with the apex of the abdomen paler; females are 1.4-1.7 mm long and males are 1.1-1.2 mm long. The legs are entirely white or yellow. The greenhouse thrips is parthenogenic, it reproduces without mating, and males are rare. The adults are poor fliers and tend to remain in the shaded areas on the plant.
The eggs are white and banana-shaped and are inserted singly in plant tissue by the females. The early larval stage is whitish with red eyes. Larvae become yellowish after feeding. Mature larvae average 1 mm in length. Greenhouse thrips undergo two larval instars then moult to the prepupal stage which is light yellow with red eyes and short wing pads. The pupal stage is slightly larger, with longer wing pads and larger eyes. It is yellowish and then darkens with age. The antennae are bent backward over the head in the pupal stage. The prepupal and pupal stages do not feed.
The black tea thrips feeds primarily on the foliage of ornamental plants. It attacks the lower surface first and, as feeding progresses and the population increases, moves to the upper surface. The leaves become discoloured and become distorted between the lateral veins. Severely damaged leaves turn yellow and drop. In addition, leaves are covered with small droplets of black excrement from the thrips.