Greenfly tend to drink the liquid, or sap, from a plant. This sap can be found in leaves, roots, or stems. Plant sap has a high concentration of sugar in it, much more than a greenfly needs, so the greenfly will excrete the excess as waste, termed ''honeydew,'' from its body.

Why do Greenfly feed from phloem?

Aphids are notorious agricultural pests as they can transmit viruses to plants. By feeding on the phloem, aphids obtain the amino acids they need. The phloem is poor in some of the essential amino acids but aphids have symbiotic bacteria (Buchnera) that can upgrade non-essential amino acids into essential ones.

Do Greenfly eat roses?

What are greenfly? Greenfly, part of a wider group of insects called aphids, are one of the most common 'pests' in our gardens. They are attracted to all types of plants and flowers because they like to eat the sap they exude. They are commonly associated with their love of roses but they can be found on any plant.