Bumblebees (Hymenoptera: Apidae: Bombus) show an incredible degree of size variation within and between species. Individuals from the same hive may vary up to 10-fold in mass. This variation allows individuals to specialize in foraging on different flowers suited to their morphology. However, as different species have different foraging behaviors, their variation and scaling of body sizes and mouthparts may have been constrained in different ways to optimize nectar collection as they coevolved with flowering plants. Here, we examined the scaling relationships between body size and mouthpart structures, and the variation in mouthpart shape between species to determine whether foraging behavior can be differentiated and inferred using these patterns. We sampled 7 bumblebee species throughout Maine, a region of high bumblebee species diversity, biogeographic variation, and diverse land-use histories. Variation in the size and shape of mouthparts was analyzed for each species using multivariate morphometric analyses to identify species and caste differences. Our results indicate that generalists, such as B.bimaculatus, B.vagans, and B.impatiens, display wider variation in the shape of mouthpart structures and isometric scaling relationships between tongue and body size, while niche species, such as B.ternarius and B.terricola, display narrow variation and canalized slopes of zero. Two species, B.borealis and B.fervidus, were strikingly different in mouthpart size and shape compared to others, perhaps due to their early evolutionary divergence from the rest of the genus. Overall, these patterns support the hypothesis that different bumblebee species have different pollination strategies: generalists have a variety of mouthparts suited for different flower species, while specialists focus on certain flowers with a consistent morphology.