A survey of insect pollinators and the foraging behavior of Carniolan honey bees (Apis mellifera carnica Pollmann) and dwarf honey bees (A. florea F.) on alfalfa flowers was conducted in May of 2013 and 2014. Fifteen insect species belonging to 11 families and 6 orders were recorded as pollinators on alfalfa flowers. The most abundant order was Hymenoptera. In comparison to the Carniolan bees, the dwarf bees were more active on alfalfa flowers. Two peaks of foraging activity for the two species were recorded; the first one was at 0800–0900 hrs, while the second and the highest peak was at 1700–1800 hrs. Carniolan bees were more active in gathering pollen at 0800–0900 hrs. It is concluded that Carniolan and dwarf honey bees were found to be the most abundant pollinators on alfalfa flowers in Saudi Arabia. The present study recommends that, to protect insect pollinators, it is advisable to apply pesticides, if needed, during the flowering period of alfalfa when the bees are not active in the fields, so as to maintain the pollinator population and protect the alfalfa crop.