New species

Horse-Leech

by Ian Bushell

During Wednesday’s working party, while planting up the new scrapes in Lambrok Meadow, I came across this leech. 

The old terracotta land-drain system is still working and drains into the new scrapes.  By the broken end of one of the pipes, I was digging out some clay to plant a Sedge plug, when I noticed the leech in the clay.  I picked it out, washed it off and put it on the pipe to photograph it. It was probably about 10cm long and it wriggled back into the clay while I was busy doing other things.

I sent the pictures to a Bristol-based entomologist, who reckons it is a Horse-Leech (Haemopis sanguisuga) a species of fresh water leech so named because of its size [up to 15cm when it is stretched out] and its similarity to Limnatis nilotica which is a blood sucking leech. Horse-Leeches are not bloodsuckers; they are incapable of biting into mammalian skin.

They prefer to eat snails and midge larvae, and will venture onto land to prey on earthworms and terrestrial invertebrates; they have been found up to 30 metres from water. Their usual habitat is in slow moving streams and ponds but they are often found living under stones near to water. They are common and widespread throughout UK and Europe.

Because it is the first time we have seen a Horse-Leech in the reserve, I added to the species list.