A white plume moth, Pterophorus pentadactyla (family Pterophoridae, order Lepidoptera). With their mis-shapen wings and large spikes on their legs, plume moths seem like they ought to be from another world. I came across this specimen while turning leaves, chasing a bug I wanted to photograph. See here for another species of plume moth that I came across a couple of weeks ago.
Photo taken in Reading University grounds, Reading, UK, on 2009-07-03.