Those bees that search for and collect food (nectar and pollen), or water and propolis, are called foragers. They are the older bees in the hive as opposed to the younger bees that are called house bees and that work exclusively within the hive. Foraging is the most dangerous of the tasks bees undertake. The life of an active forager is short, two or three weeks of field duty, because of the demands on the bee’s body. A small percentage of foragers are scouts and find the food that the rest of the foragers collect; the rest of the foragers follow the recommendations of the scouts. The distance over which bees fly to collect food is quite variable, and depends on the available resources. In agricultural settings with abundant floral resources, the median distance can be just a few hundred yards. Under less rich conditions, however, some bees may forage six or more miles from their colony. Bees probably forage over large areas not because of no resources closer to their hives, but because the greater distance increases the choices of foraging patches and allows a colony to increase the average richness of the the patches it utilizes. As the distance from the colony to forage increases, the profitability of foraging falls off due to an increase in the time required for flight and the energy consumed during flight. Due to their concentration or relatively nearby sources, bee colonies compete most strongly with nearby hives. Therefore, colonies in small apiaries collect more honey than do those in large apiaries. The usual practice is to place apiaries two to three miles apart to minimize competition between them.