The sense of taste facilitates rapid decisions about whether to ingest or reject food. The extent to which information beyond the basic modalities (e.g. sweet, bitter, salty) is represented by the peripheral taste system has rarely been studied. Carbohydrates are critical nutrients for many insects detected by sugar-sensing gustatory neurons (GRNs) that elicit action potentials (spikes) in response to stimulation. Here, we show that GRN activity on the mouthparts of the buff-tailed bumblebee, Bombus terrestris, represents the molecular identity of sugars. Sugars with the highest metabolic value had the lowest detection thresholds and produced the greatest rate of change in spiking in the most active sugar-sensing GRN. High value sugars also always elicited coherent bursts of spikes involving two of the four GRNs in each gustatory sensillum. Sugar molecular identity could not be determined using the rate of spiking or bursting of these GRNs alone. Stimulation with sugars of little or no metabolic value generally failed to elicit spikes and did not evoke feeding. Furthermore, toxic sugars inhibited the responses of sugar-sensing GRNs to sucrose. Activation of a third GRN provided information about sugar molecular identity. This GRN spiked selectively to relatively high concentrations of the nectar sugars, fructose, sucrose, and glucose. Our data show that information about sugar metabolic value and identity is encoded by a population of GRNs in each sensillum. This information guides bee feeding behaviour through its effect on the proboscis extension reflex and time in contact with food.