I have recently (1 year ago) read "BUG WATER" by Arlen Thomason, which deals with bugs in their aquatic environment. Very pictorial and informative and alot of info in there. In one coversation with TAXON, online in this forum, he had a link to what I believe was a NW emergence chart and it was incredible and worth finding and printing for a chart on whats "what" and when its coming online in the time of the year. Very good info. I have, but have yet to read Dave Whitlock's Guide to Aquatic Trout Foods and I believe it is also good. I have also picked up and read many of Dave Hughes books which are very good and he has one, I haven't read yet, but you mentioned Mayflies, One of his books on Mayflies is ..."Mayflies... everything you need to know to match any mayfly you'll ever encounter". I have yet to read it as well but its on the list. Anything written by Gary LaFontaine is excellent and especially .."Caddisflies" and I am presently finishing "The Dry Fly.. New Angles". LaFontaine's books are excellent and also discusses methods of fishing the flies as well as the insect life applicable to the water setting and fishing. Sometimes it may be a little technical and tough sledding to read but very good in depth information on his research with insects and fly fishing. I sometimes find some amazing books at a very reasonable price at Half Price Books and also thrift stores around. I have also bought new books from fly shops. Like to find the ones I really want to keep forever and buy them new but I have found treasures as used books. Don't overlook the fellow, "TAXON" who is incredibly informed with insects and also a really nice guy and so helpful to all. Hope I didn't get too carried away. Good luck.