Bumble Bees of North America: An Identification Guide , by Paul H. Williams, Robbin W. Thorp, Leif L. Richardson, and Sheila R. Colla, Princeton University Press (http://press.princeton.edu), 2014, 208 pages, $24.95
With spring upon us, the timely arrival of Bumble Bees of North America on bookstore shelves is as welcome as its namesake insects are in gardens. The bumble bee’s dutiful attention to attending (and pollinating) flowers as they forage for pollen makes them an invaluable natural ally and a critical asset to our planet’s fragile ecosystems. But for a species we depend on so intimately for our food supply, there is surprising difficultly in clearly distinguishing between species – even among bee systematists – without the illumination of molecular analysis. Without such modern amenities in the field, entomologists are left to untangle species from hair color patterns, a maneuver further complicated by caste (queen or worker), or morphological characteristics of the face and genitalia which, for the layperson, is often too close for comfort.
Given that the last comprehensive guide to North American bumble bees was published in 1913, Williams, Thorps, Richardson, and Colla’s Bumble Bees of North America offers a much-needed review of the status and identification of the 46 bumble bee species north of Mexico. Notwithstanding several cursory chapters on natural history, bumble bee forage by ecoregion, or decline and conservation, Bumble Bees of North America is otherwise a species identification guide based on four principal groups derived from either a quick, simple key (p 50), or an advanced main key (p 168-198) that requires a microscope or hand lens. Especially helpful are the color plates that illustrate a majority of the keys’ couplets. Accompanying each species entry are the expected distribution maps, representative photos, and identification characters, as well as diagnostic color-pattern diagrams meant to illustrate the hair color patterns.
Where the guide appears to fall short is its failure to provide direction on how to actually read the color-pattern diagrams, which should be the guide’s hallmark feature. Take the characters of the Vosnesensky bumble bee, described to have “Hair of metasomal T3 black (contrast B. vandykei), T4 almost entirely yellow with just a few black hairs near the midline (contrast B. caliginosus, B. vandykei), S2-5 with black fringes at the back (contrast B. caliginosus) or very rarely with yellow at the sides” and “Male… hair color pattern… metasomal T5 at the sides with yellow”. It was only after I carefully reexamined the guide cover-to-cover to make sure I hadn’t overlooked an introductory paragraph or legend that I found a diagrammatic figure in the glossary that included among the labels “Tergum (T)” and “Sternum (S)”, which led me to glossary definitions for each term. A simple diagrammatic figure laying out each T# and S# plate designation on a sample color-pattern diagram preceding either of the keys would have gone a long way toward easing a layperson effortlessly into the keys.
That being said, Bumble Bees of North America marks a much-needed milestone in the ability of scientists and citizens alike to sort bee species found afield and at home. With bees on the decline, the ability to identify and inventory the buzz in our backyards may prove critical in future conservation efforts.