Mealybugs and scales
most species of mealybugs feed on the aerial parts of the plant, some species extract their nourishment from roots, whilst others are gall-formers. A few [...] gain an adequate intake of protein, mealybugs must ingest large quantities of sap, getting rid of the excess sugars in the form of honeydew. Characteristically [...] sale. A very small population can thus cause considerable loss of value. Soft scales feed mostly on leaves and twigs, causing discolouration of foliage