Small (2 mm) white flying insects, a little like tiny moths can be seen flying around infested plants and a cloud of these insects rises if the foliage is disturbed. If the under-side of foliage is examined, the immature non-flying nymph stage will be seen, and these must be eliminated to control whitefly, in addition to the adults. The nymphs secrete a sugary honeydew substance that encourages black mould on plants.