Rose aphids (Macrosiphon rosae) on a rose stem. - stock photo

A cluster of Rose aphids (Macrosiphon rosae) on a rose stem. Known as plant lice, aphids are specialised plant feeders that suck the sap from plant veins. These female insect bugs are green or pink in colour; they multiply rapidly, and a variety of aphid sizes and ages are evident here. Aphids are serious pests of flowers, vegetables and some fruit trees. Macrosiphon rosae appears in large numbers in spring along the stems and under the leaves of domestic roses.