This year has been the worst I can remember for Blackfly on my climbing French beans. The Black Bean Aphid, Aphis fabae, is the culprit and nothing I do seems to reduce the infestations. I don’t spray with chemicals so every control is organic or mechanical and despite washing them off with a hosepipe and rubbing them off with my fingers, they are back in even greater numbers the next day.
The bean harvest is in full swing but really, would you eat these?! The upside, if there is one, is that I am supporting the local ladybird and hoverfly population as they and their larvae are having quite a feast themselves!