Why Did the Chicken Cross the Road?

To get to the otherside.  

The chicken crossed the road to get to the otherside.

Why did the Deschutes Rainbow Trout Eat this Fly?

To eat. 

To eat to survive.

That's why the fish ate the fly.

Why does a native Redside Trout in the Deschutes River eat a Red and Silver Chubby Chernobyl in Fall long after the Stonefly Hatches of Spring?  Is it a crude imitiation of the October Caddis or the fading hoppers of summer?  Is it an urge to fatten up at all costs before the onset of winter? Why would any fish eat a red fly or purple for that matter?   A well-presented fly of any color and appropriate size will outfish the"perfect" hatch match fly all day long.  

Make each cast count.  Make the first cast count. Be ready.  Fish are in closer than you think.  Believe in the fly you are casting or don't bother casting.  Don't overthink the sport.  The fish eats the fly to survive.