A common pest, infatuated with broad beans in particular. So should you be worried? And how should you deal with them?

Black fly are aphids. They love to eat young, green growth. They puncture the leaves and drink the sap. In small numbers, they are of little concern. But the cumulative effects of large concentrations of blackfly can seriously weaken a plant. They can also act as a 'vector' for disease, which means that they can potentially transmit diseases from plant to plant.

Sometimes you will see ants on the same plant as the blackfly. These are feeding on the honeydew, a sweet substance secreted by the aphids - not the aphids themselves! In terms of their natural foes, ladybirds love to eat them. Some 

Here are other possible remedies:

- sowing the beans early, for example in autumn, Early crops are less likely to get attacked. 
- later on, pinching out the growing tips once the first beans have formed
- spray them with a weak solution of washing up liquid, every few days. Or using special organic horticultural soaps. 
- planting sacrificial crops such as nasturtiums around the beans
- planting poached egg plant to attract beneficial insect