Chip, I've tried the fan idea and another problem is that the bugs hit the water but most of them just take off and fly away again. I came to the conclusion that you need to knock them down. Even with this design if they don't get hit too hard they still hit the water and fly away. My design does have a fan to cool the motor. The fan blows downward which does tend to blow bugs down into the pond even if they don't get hit by the whacker. They mostly just fly away again. I checked on the parts I bought and the motor is only 1/40 hp. So it doesn't take much power but this is the smallest motor I found that will swing a trimmer line of any length. Another idea I've tried is to make the fan unit that you talk about but have the bugs blown into a mesh bag. You can run this all night and then the next day just dump the bugs into the pond as feed. I would sometimes catch 10 lbs of bugs a night. By the time they sat packed in the bag all night most were dead but the fish still eat 'em and they don't fly away.

Gotta get back to fishin!