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. Some plant viruses, especially of Strawberry and raspberries, cucumbers can be spread via mouth parts of aphids as they move from plant to plant.
Product solution: On outdoor lettuce Provado Ultimate Fruit and Vegetable Bug Killer - concentrate / ready to use. Indoor and outdoor lettuce, Provado Ultimate Bug killer ready to use, Sprayday Greenfly Killer, Organic Bug Free, Natria Bug Control. For indoor lettuce hang up Greenhouse Flycatchers wherever possible.
Cultural control: Encourage birds into the garden to feed on the aphids ie Blue Tits.