Mealybugs and scales
In order to gain an adequate intake of protein, mealybugs must ingest large quantities of sap, getting rid of the excess sugars in the form of honeydew [...] 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 species [...] is usually the first sign of the presence of this type of pest. Among ornamental crops, ferns are particularly sensitive to soft scales, as are oleanders