Well I can categorically say "We have trapped horse flies." We got the whole thing set up Sunday afternoon and by evening had a pretty good catch - considering it was just a few hours before dark. Monday was better but I thought the flies weren't as active as some days. Today after a rain and hot and humid weather we got quite a few flies. YEAH!!!!! But they are still bothering the cows so we might have to move the whole contraption to a new site that might catch more. (did I use 'might' twice in one sentence - you might think I've become a political reporter) Anyway any dead horse fly is a GOOD horse fly!! Oops! Any dead female horse fly is a good horse fly !! (i got the picture from www.emilyware.co.uk/blogs/index.php/2009/03/17/biters?blog=5)