The honeybee can reach the nectar from the mouth of the hairy vetch blossom by tripping it, or she can insert her tongue between the petals at the base of the corolla tube and reach the nectar. These non-trippers are called base workers. The foraging method is learned and becomes fixed through success at foraging from a very few blossoms in one manner during almost random attempts to reach the nectar. A slightly larger percentage of trippers reached the nectar by inserting the tongue to their right than to their left of the sexual column. There were never many bees in the field that foraged some blossoms as trippers and others as base workers, nor were there many that foraged for pollen only. When there was a good nectar flow early in the season there were few bees foraging as base workers, and the number of trippers foraging for nectar only was about equal to the number gathering both pollen and nectar. After a few days with a poor nectar flow the percentage of tripping bees gathering nectar only decreased sharply, the percentage gathering both nectar and pollen increased slightly, and the percentage of base workers increased sharply. There was a larger proportion of base workers in vetch with scattered blossoms than in vetch with numerous blossoms, and also a larger proportion of base workers in vetch with a heavy aphid infestation than in vetch in which these insects were controlled. During a poor nectar flow base worker gathered larger loads of nectar than trippers. To explain these observations, it is proposed that bees prefer to gather nectar which yields the greatest return in sugar per unit expenditure of energy, and that base workers expend less energy in foraging from blossoms than trippers. It is believed that base workers are more sensitive than trippers to competing foragers, and thus are more likely to be forced into areas with the least competition, that as the nectar flow deteriorates more trippers than base workers cease to forage, and that most of the bees that normally trip blossoms but have had some experience as base workers, and possibly some other trippers, begin to forage exclusively as base workers.