Bumble bees (Bombini) are among the more familiar creatures inhabiting meadows, gardens and grasslands of the temperate world. Robust and vividly colored, they emerge from hibernation in early Spring in far northerly latitudes, feeding from the earliest willow blossoms before the snows have fully melted. Thermoregulatory mechanisms maintain their body temperature high above ambient in cold to freezing weather, allowing them full activity under conditions too extreme for other bees. Although they are most abundant in alpine and high-elevation grassland habitats of the northern temperate zone, they range widely from Greenland to the Amazon Basin, from sea level to altitudes of 5800 m in the Himalayas. Thus bumble bees exploit a wide diversity of habitats, from alpine meadows to lowland tropical forest. Nonetheless, they appear similar in morphology throughout their range suggesting that ecological opportunity and behavioral adaptations play an important role in colonizing diverse habitats. Despite the apparent constraint on structural diversity, bumble bees display striking inter- and intraspecific variation in color pattern across their range, purportedly the outcome of mimetic evolution. Not only are Bombus predisposed to converge sympatrically on similar color patterns but other insects mimic the Bombus patterns, thus providing excellent opportunities to examine the influence of natural selection on the generation of variation among Müllerian and Batesian mimics. Elucidating the evolution of diversity requires knowledge of the historical pattern of variation, which, in turn, provides unique insights into evolutionary processes underlying the pattern of variation. A robust phylogeny of Bombus of the world, now published from our lab (Cameron et al 2007), is essential for inferring the history of their wide geographic distribution (Hines 2008) and for testing hypotheses of behavioral and mimetic adaptations. Our lab is now in the process of reclassifying the bumble bees as a result of the new phylogeny (Williams et al 2008). Photos: Heather M. Hines.