[Frog]

My runner beans and rhubarb are absolutely smothered in blackfly. Have noticed lots of ants crawling all over the plants too. Have spotted a few ladybirds around aswell, but not enough to get rid of all of the blackfly. Now wasps have joined in and are flying around both plants too! 

Do the wasps eat the aphids or are they after the ants or ladybirds or none of them? Not sure which to tackle first. Any suggestions?

[mumofstig]

Ants help the blackfly - ladybird and wasps kill the blackfly.
Spray the blackfly late in the evening, so you don't harm the good guys

[Frog]

Many thanks MoS!

Was wondering what was going to arrive next  and whether I was going to get anywhere near the plants again 

[Paul Plots]

Are you sure you have wasps flitting about too?

Is it possible that they might be hoverflies? These little darlings are really quite helpful. The larvae of hoverflies enjoy snacking on aphids so maybe that's why they are busy around your beans?