Why brim swat surface flies?

[Eight Thumbs]

Hello All,

I've asked this question before but we have lots of new people at FAOL and I'm hoping that I might get a definitive answer. I love to fish for brim on the surface during those warm spring days which will be coming soon. Most of the time, I catch fish after fish on Griffith Gnats, EHCs, and Gurgle Pops. But, there are those occasional days where the fish are very active but refuse to actually "bite" the fly. They vigorous swat the fly with their tail or roll their whole body over the fly, often with a major splash. I set the hook on these "false strikes" again and again without a hook up. I should add that this often occurs to the total amusement of various onlookers who already think that fly fishing very strange and highly deviant. "That wouldn't happen with worms, ya know!"

Two questions.

Why do brim show this aggressive behavior toward a poor little fly if hunger isn't the motive? Even if they are bedding, surface flies present little threat to the nest. Just meanness? Just for fun? Just for laughs?

What do you do when this situation occurs? I've tried going to wets but often more often than not, the brim continue to toy with these as well. Any ideas?

Thanks in advance for you thoughts on this dilemma. 8T