Mealybugs and scales
plant sap, mealybugs and soft scales also produce honeydew (on which moulds grow) resulting in considerable damage in ornamental and fruit crops and loss [...] defoliation. The overall effect reduces photosynthesis and therefore the yield. Where flowers and fruit are concerned, these often drop off; plant sap is low in [...] Characteristically, dark sooty moulds ( Cladosporium spp.) are often found growing on this honeydew, which, as well as the white, waxy secretion of the mealybugs