Somewhat of a generic approach, but it "should" work as it works against many types of gnats and flies here.
Wear long sleeves and full length pants.
Get some pure DEET (100% stuff, not the low concentration of many popular brands) and rub it on exposed skin, save for the parts that might let sweat get it in your eyes.
Light up a King Ed cigar, any insect caught in the cross-fire will surely die.
Go outside only when there is a breeze.