The bug, Hydrometra stagnorum, found at Swanwick NR, Hampshire in 2003.
The bug, Hydrometra stagnorum, may be observed around the plant-covered margins of ponds, ditches and slow-moving streams. They move slowly on the surface of the water in search of prey: it is this unhurried movement which gives rise to its name of ‘common water measurer’ – moving as though they are carefully recording the distance they had travelled!
Water-measurers use vibrations made in the surface film of the water to locate their usual prey, mosquito larvae and water fleas, which they then impale with their needle-like mouthparts. They will also scavenge on dead insects floating on the water surface,