However, except for honey bees, it remains poorly known how bees manipulate and process nectar in order to concentrate it. One way bees can deal with nectar with a low sugar concentration is by concentrating the nectar themselves (Corbet and Willmer 1980 Bertsch 1984). In addition, bees that drink nectar via suction (rather than lapping) forage more efficiently on lower nectar concentrations (Borrell 2004 Kim et al. In general, bees prefer nectar with higher sugar concentration than is generally provided by plants (Roubik and Buchmann 1984 Roubik et al. The sugar concentration of nectar is variable and depends on the plant species, individual, weather, rate of removal by pollinators, and time of day, among other factors (Corbet 1978 Corbet et al. Nectar is used by bees for their own energetic needs as well as part of the provisions for their larvae. Our methods highlight how community science images validated by experts represent a rapidly growing source for aggregating novel behavioral data. Nectar concentrating has various purposes, including preparation for long-term storage in hives, modification before adding to larval provisions, removal of excess water for efficient storage in the crop, thermoregulation, and potentially for nest construction. It is especially conspicuous in halictid and hylaeine bees. We find this behavior to be taxonomically widespread, with observations of nectar concentrating behavior documented in 51 genera in six families. Here, we combine accounts and images from publications, community science portals, and our field observations to document the breadth of nectar concentrating behavior in bees. However, observations of this behavior in disparate bee groups suggest this behavior is widespread. It has long been known that some bees concentrate nectar externally with their mouthparts, including honey bees and stingless bees. Nectar is one of the most important resources used by bees.

Parts of a nectar flower