Many flowering plants produce nectar containing low doses of caffeine. In laboratory experiments, honeybees rewarded with caffeinated nectar were about three times as likely to remember a flower’s scent a day later as bees rewarded with plain nectar, and some researchers have suggested that caffeine therefore benefits plants by making pollinators more loyal to them. A later study complicated this picture: bees feeding on caffeinated nectar kept returning to the source, and kept recruiting nestmates to it, even after its sugar content had been reduced to levels well below that of nearby uncaffeinated flowers. This suggests that