There are little black flies called Blandford Bombers here. When I get bitten by them I swell up terribly. They can only get about .5m off the ground so it tends to be my legs and ankles that get bitten while cycling. I am left with a bruise for a couple of weeks afterwards.
Walmart compression socks will do that. Currently googling to see if there's flies/bugs that bite and inflame legs.