They are gross things. Got my legs covered in them walking near Cape Wrath last year. I had long trousers on and long walking socks, but they weren't tucked in, so they still managed to get in and crawl up the legs.
Have some touring planned in a couple of weeks in Eastern Europe with some wild-camping and off-roading hopefully, totally forgot they transmit encephalitis there too and no time to get a jab now. Oh well will just have to be careful.
If you leave them on they swell up about the size of a small pea, more grossness. Still more grossness if you pop them.