In reply to Heike:
I've just come back from KwaZulu Natal where they were a blessed nuisance. When we were out in the hills we had to keep stopping and checking our legs, socks and clothes. Every day I found up to half a dozen on me. You have to pick them off before they get a hold.
But it is mid summer over there....
Seriously though before setting out in the morning, I tried rubbing Tabbard on my legs and sprayed my socks and shorts with an insect repellent. This really worked and once I started doing that they stopped.