AbstractIn laboratory colonies, 8 temperate Bombus Latreille species and the tropical montane species, B. ephippiatus Say, had significantly more first-brood workers, more rapid worker development time, and faster rates of worker production than the tropical lowland species, B. atratus Franklin. Bombus ephippiatus did not differ from most temperate species in any of the 3 characters. Differences in these bionomic characters among arctic, temperate, and tropical Bombus are assessed in terms of latitudinal trends.