A Leech

I cannot recall having seen a leech for years but I netted one in the pond today while clearing out some duckweed.






I think this is a Horse Leech (Haemopis sanguisuga) which, despite its name, does not feed on mammal blood but on snails, midge larvae and worms. They are common under stones near the banks of lakes and in ponds and ditches, often just under the water surface.