Does anyone know how to get rid of the black insects on these plants? Do they do any harm?
Hi - I think they're blackfly (anyone - please correct me if I'm wrong). They look just like greenfly - except for the colour, of course.
They suck the sap out of the stems.
As with all aphids, the best natural control is ladybirds - especially their larvae. Yum, yum.
If there aren't any ladybirds around, you can wash them off with a soap water solution, and / or squish them with your fingers.
If you want to go down the chemical route, try a search for aphid pesticides.
Hope that helps.
blackfly adore them this is why good to grow them as a companion plant near broad beans for one :)
Thanks for both your replies, very helpful, i'll plant some in my bean/pea bed