Interesting and useful information from Lesley Wickham (thanks!) …
Most of us on the recent Ryton Hills walk had close-up encounters with leeches. These little devils have a three-pointed star-shaped biting mouth which slices through skin and some clothing. Although they sometimes drop from shrubs, mostly they get onto the body from the ground and tend to climb up until they reach somewhere they can hide while they feed, like an elastic clothing edge or a watchband.
People generally expect to find them in wet places but our experience has shown that there are varieties, usually larger than the wetland varieties, which like dry places so they can strike unexpectedly when you don’t think you’re in an area which favours them.
In ‘biting’ the leech releases an anti-coagulant and an irritant into the bloodstream to encourage flow. This is what causes the swelling and itching following a bite and makes it difficult to stop the blood flow when they’re pulled off.
If you’re familiar with their bites, you will often notice a vague, difficult to pin down itch as they start to attach which can be a warning to check. If you get them off before they start to feed, you can avoid most of the after-effects. If allowed to feed until full, they withdraw most of their secretions before dropping off, so the subsequent bleeding and itching are considerably reduced. This can be disturbing if you’re not used to leeches and many people are too horrified to leave them once they know they’re there but the results are usually better if you can resist the temptation to interfere.
Styptic pencils, available from chemists, can be used in the field to stem bleeding as sometimes they will even soak and bleed out around a bandaid.
Many preventions can reduce the risk. Having lived in an area abounding with leeches, we found that wearing knee-high stockings (“trouser socks”) under bushwalking socks was a big help as they will burrow through the fabric of the socks if they can but can’t bite through the stocking. When we removed our socks, we would often have numbers of half-dead miserable leeches trapped between the layers, unable to move or bite. Putting a smear or spray of insect repellent round elastic clothing edges, round the neckline of teeshirts, round your watchband and on the outside of boots and/or gaiters can also help.
A friend of mine heard that dishwashing detergent was a good deterrent, so she smeared it over her boots before a walk. All went really well until we had to go through a water crossing, after which her boots developed a magnificent halo of foam, a source of great hilarity to the rest of us on the walk.