By Miner
Derbyshire,
United Kingdom 
my runner bean leaves were attacked by a wart like swelling on top and a small perfectly round white circular laying of what seemed like eggs under the leaves.doesnt sound like halo blight.have seen leaf miner before its not this.thanks for trying.
19 Oct, 2010
It could be leaf miner, get one out with the blade of a knife, pick off the leaves and destroy them.
19 Oct, 2010