Bass are what are called 'engulf' feeders.

They capture their prey by rapidly opening their mouths and flaring their gills, creating a vacuum that pulls in both the food and a large amount of water. Once the prey is inside the mouth, the bass kills it by crushing it between two crushing plates located on the roof of the mouth and lower jaw, expelling the excess water through the gill opeings.

This should give you some insight into how to construct flies for bass and when to set the hook. It also explains why bass sometimes miss a fly, and why sometimes WE miss the bass.

It's also 'the' major difference between how a bass eats and how a trout eats.

Good Luck!