Blackfly – Latin name: Aphis fabae (in the family of Aphididae)
Blackfly is a serious pest of broadbeans in the kitchen garden. A whole mass of shiny black insects cover the growing tips, flower buds and the underside of young leaves of the broad bean plant.
Keep a sharp look out for blackfly on spring-sown beans when they are in flower in June. One advantage of sowing broad beans in the autumn is that they tend to flower early, producing beans in May or June, before any blackfly appear.
Blackfly suck the sap from the broad bean plant causing stunted growth with curled, distorted leaves, and poor crop yields.
Discourage blackfly attack by pinching out the growing tips of the broad bean plants when they are in full flower. Some gardeners pinch out the tops when five flowers have formed, or when the first pods have set. Remember the pinched out tops may be cooked & eaten! The tops can be steamed as a green vegetable or used in a broad bean top omelette.
- wash or spray the plant with a mild soap solution
- encourage their natural enemies – ladybirds, hoverfly larvae, lacewing larvae and parasitic wasps
- use an insecticide:
Contact insecticides work when they actually touch the blackfly. They have short persistence, so thorough treatment, especially of the underside of leaves, is necessary. Aphids protected by curled leaves are unlikely to be controlled.
Synthetic pesticides generally give a higher level of control. Always read the label for instructions on the use of the product and harvest intervals. The harvest interval is the period of time between spraying the crop and it being safe to eat.