Blackfly and greenfly (aphids) are very common sap sucking pests affecting nearly all types of plants. Colonies are visible around new buds or shoots in spring onwards. Leaves may twist or yellow and become puckered and distorted as they develop. Product solution: Sprayday Greenfly Killer, Provado Ultimate Fruit and Vegetable Bug Killer - ready to use/concentrate, Organic Bug Free, Natria Bug Control. Encourage birds into the garden to feed on the aphids ie Blue Tits.