"A fly has, on average 350,000 neurons," he said. "Most of them dedicated to processing sensory information."Two-thirds to three-quarters of the brain are devoted to the eyes alone. It flies with great dexterity and precision, using only some of the remaining neurons. And yet, packed into this relatively small bunch of brain cells are all the instructions for flight maneuvers. Unlike mammals or birds, the fly doesn't have to learn anything.
"When a fly breaks out of its pupa, it can fly as well as it ever will," he said. Human beings seem to think that being constructed so that people learn complex behaviors is a superior life plan, Dr. Dickinson said. But it was an equally challenging evolutionary problem to make a brain about the size of a poppy seed, in the case of the fruit fly, "that can do everything in the behavioral repertory of a fly."
There were so many straight lines in this post I found it hard to restrain myself in light of certain tasteless jokes. However, it is something to comment upon that the fruit fly(arrghh) uses the rest of its brain to smell, taste, feel/hear, coordinate those and other things to survive and reproduce. SWAT!!! To a certain degree.(WHEW! made it without firing a shot)