Yesterday, in Chatsworth, the flies were super-aggressive. This must be the new brood. I was hassled the entire time I was out there. I had to carry a branch from a bush and swing it around my head constantly (this works in a pinch). Usually they back off, but these flies were like kamikaze fighter pilots. They tried to get in-between the swings, and they'd often end up crashing into the branch.
I had to get back at them today, so I pulled out my old straw hat, wrapped it in blue banding, and covered it with "tanglefoot" sticky coating. Always wanted to try this. So what happened was, I'd hear them approach me, and then just as fast, they were gone. I thought maybe they got a whiff of it and took off. But no, I took it off to see, and watched a fly hit it, he realizes his feet were stuck, and beat his wings just enough to disentangle himself, and with panic and relief, he flew off. So really, it worked even better than I thought. They land on your hat more than we know, and the blue really pulls them in. Some of them don't make it, as you can see. A few of these were on their backs in the goo. They probably flipped over when they tried to untangle their feet. Good!