Pest that feed on YOUR plants have different feeding behaviours, including chewing, sucking, mining, wood-boring and gall-forming. Most insect pests that attack ornamental plants grown in greenhouses and nurseries have sucking or piercing-sucking mouthparts; these include aphids, whiteflies, mealy bugs, certain leafhoppers and soft scales. These insects insert their mouthparts into the food-conducting tissues (phloem) and withdraw plant fluids. Insects with piercing-sucking mouthparts tend to ingest large quantities of plant sap. They then produce honeydew, a clear, sticky liquid that serves as a growing medium for sooty mould fungi, which causes a black coating on leaves that can interfere with the plant’s ability to photosynthesize.