Prurient readers titillated by the title will be disappointed. The only references to sex and death in this book have to do with the behavior of bugs - mayflies that is.
Here's an example. "A mayfly spinner lies on the surface of the stream in what fishermen call the `spent' position. To picture it accurately remember that the insect has just had the first and only orgasm of its life and is now, in the natural course of things, dying from it. His body lies flush with the water, wings spread, legs out flat, tails splayed wistfully. Usually he's limp. If he struggles at all, he does it feebly at best. There's probably a silly look on his face, although it's hard to tell with insects".
So accept it. What this book really is about is fly fishing, and the sex and death are there just to hook you. But can this kind of stuff also reel you in? You'll find yourself wading through material such as the following: "I tied on a #14 Michigan Chocolate spinner, a fly that A.K. had turned me onto years before. This thing has fine split tails of pale dun hackle fibers, spent hen hackle wings of the same color, and a thinly dubbed, dark brown body...".
You would think that this kind of gobbledygook would be accessible and interesting to hard core fisherpeople only, but it's not the case. I've never fly fished, and I was captivated by it.
I think the author puts it well: "I don't know exactly what fly fishing teaches us, but I think it's something we need to know".