Oligonychus coffeae is most destructive pest in all tea growing areas of India causing considerable yield loss.
Life cycle and appearance
The life cycle of spider mites includes eggs, larva, protonymph, deutonymph and adult with quiescent stages in between two successive active stages. Females lays 40 to 50 eggs in their life cycle. The blood red colour eggs are laid all along the veins and mid-rib on upper surface of the leaves. Freshly hatched larva is yellow orange and the larval period is followed by the first quiescent stage. The protonymph has four pairs of legs. Deutonymphs are like protonymphs but they are larger. Males are short lived where as females live for 3 weeks during summer period and couple of months during winter. The life cycle is shorter (10-12 days) during summer period and it takes longer period of 28 days in colder weather. Tea spider mites completes 22 life cycle per year.
Larvae, nymphs and adults causes damage to the tea plant which sucks the sap of leaves and occasionally on petioles. Red spider mite attacks the upper surface of the mature leaves. Infestation starts all along the veins and midrib and gradually spreads to entire leaf. Youngs leaves are also equally affected. Infested leaves become reddish bronze and spider mite infested fields can be identified from a long distance as patches. Infestation results in reduced photosynthetic activity of leaves, subsequently leaves wilt and defoliation occurs due to increased transpiration and moisture loss. Absence of shade, high temperature and dry conditions are congenial conditions for pest outbreak.