blackfly - spray with hand soap or washing up liquid?

[linspins]

I have loads and loads of blackfly on my runner bean plants, and have read that spraying with a soapy solution gets rid of them. But do I use liquid hand soap or washing up liquid (- I've got Ecover versions of both)? I would blast them with water alone but hosepipe doesn't reach that far!
Many thanks.

bump?

I normally use fairy liquid; but I'm not sure it matters. It'll be the detergent that helps get rid I think rather than anything more specific. What I did was made up an icecream tub with loads of washing up liquid (about 1:10 with water). Then dip in a j-cloth or kitchen roll and wipe off the aphids. I found that more effective for the big clumps and less likely to damage the plant than squirting.

Thanks Freebuttonbee!