A great description from the Xerces Society: "More than ever before, there is widespread interest in studying bumble bees and the critical role they play in our ecosystems. Bumble Bees of North America is the first comprehensive guide to North American bumble bees to be published in more than a century. Richly illustrated with color photographs, diagrams, range maps, and graphs of seasonal activity patterns, this guide allows amateur and professional naturalists to identify all 46 bumble bee species found north of Mexico and to understand their ecology and changing geographic distributions."

We agree ... this is a great reference work that you will rely on for many years to come. It's detailed, yet written in a form that's accessible to even the novice. The subtitle is "An Identification Guide" and it includes loads of detail, and even a section on Keys to Identification of Male and Female Bumble Bees. 

208 pages, Paperback

NOTE: Books are subject to only 5% tax ... a nice savings for book lovers.