If you want to understand streams and how to fish them, this book by Rick Hafele is a must-read! The author has a Masters degree in aquatic entomology with a minor in fisheries biology. For over 30 years Rick has been able to watch and study fish and the insects they eat, both professionally and with a fly rod in his hand while fishing in Oregon and many other states and provinces. Rick started fly fishing over 50 years ago, 40 of which have been focused on fishing for trout in streams and lakes throughout the west.