A red spider mite, Tetranychus urticae, on a leaf of a tomato plant growing in a greenhouse. The picture shows the mite together with the web it spins (fine white fibres) to secure its hold on the leaf surface. Spider mites are a serious pest of many greenhouse grown plants, including cucumbers, aubergines, peaches and grapevines. They feed on sap, initially causing leaf mottling, but heavy infestations can result in the loss of foliage and faiiure of the crop. A female mite lays around 100 eggs. In a warm greenhouse, these grow to adulthood in less than 10 days. Chemical control is difficult due to the ability of the mites to develop resistance. A simple method of control in a amateur greenhouse is repeatedly to spray affected leaves with water. A predatory mite from Chile, Phytoscilius persimilis is used commercially as an organic pest control agent. Mag x 160 at 10x