green fly?

have just been doing the old patrol of the garden when i stumbled across my lupins when on closer inspection noted that flower heads was absolutly covered in flys , now i say green fly but what are the chances of it being green fly and how easy is it to eradticate it , i can see the plant failing if tehre not dealt with. cheers

 

http://www.rhs.org.uk/advice/profile?PID=653
There was an article on Gardeners Question Time on the radio yesterday about Lupin Aphids , could it be these ?