Frank's post and video sure brought back fond memories. I don't want to divert the topic to bluegills but obviously crappies and bluegills feed a lot on the same things.
So Labor Day 2015 our family had the last big picnic of the summer at "the lake." After the gang went home my wife and I stayed at our cottage to clean up. Towards evening, when the "water jockeys" were on shore and the lake calmed down I decided to troll for a while. As I approached the far side of the lake I noticed a bunch of seagulls on the water, picking like a flock of chickens. They were obviously feeding on "something." As I got closer they all took off. As the water smoothed out from their departure I noticed a lot of "boils," obviously from feeding fish. I shut down the motor and grabbed my ultralight. I pulled a #6 aberdeen, a small bobber(not clear), and a bottle of Gulp worms from my vest. I cast that rig towards the circles on the water and the bobber kept going....down. The first fish was a "keeper" bluegill. In about a half hour I had my limit of bluegills.
The next morning I was on the deck with binoculars watching the flat surface of the lake for disturbances, and there were plenty. It didn't take long to catch 25 keepers. Long story short, my wife kept count and I was out there 27 of 31 days in October, and 5 of those were morning and evening trips. I've fished that lake for almost 50 years and that was the fastest bluegill fishing I have EVER had. I never did SEE what those bluegills were feeding on but I assume it was zooplankton that would require magnification to identify. I never did catch any crappies. The good Lord willing I'll get to experience that again in the fall of 2016. Here are a few photos of an October I'll remember forever.

Deck view. You can see the disturbances out where the trees reflect on the calm water.



Feeding bluegills spooked by the boat.



You can see how close the bobber is to the hook.



If fish is indeed "brain food" I ought to be a genius.