A worker bee is a female bee that lacks the full reprouctive capacity of the colony's queen bee. The worker bees keep the hive temperature uniform in the critical brood area (where new bees are raised). Worker bees gather pollen which they stick to combs in their back legs, to carry back to the hive where it is used as food for the developing brood. Pollen from the stamens of one flower, carried on their bodies, is carried to another flower where a small portion rubs off onto the pistil, resulting in cross pollination. (Bees and flowering plants co-evolved many millions of years ago.) Almost all of civilization's food supply (maize is a noteworthy exception) depends greatly on crop pollination by honeybees, whether directly eaten or used as forage crops for animals that produce milk and meat. Nectar is sucked up through the proboscis, mixed with enzymes in the stomach, and carried back to the hive, where it is stored in wax cells and evaporated into honey. Worker bees must maintain the hive's brood chamber at 34.4 degrees C to incubate the eggs. If it is too hot, they collect water and deposit it around the hive, then fan air through with their wings causing cooling by evaporation. If it is too cold, they cluster together to generate body heat. The life of all honeybees starts as an egg, about the size of a comma "," which is laid by the queen in the bottom of a wax cell in the brood area of a hive. A worker egg hatches after 3 days into a larva. Nurse bees feed it royal jelly at first, then pollen & honey for 6 days. It then becomes an inactive pupa. The honey comb has hexagon cells on both sides of a vertical central wall. As shown in the photo, these cells are inclined upward, primarily to retain liquid nectar and honey. During its 14 days as a pupa, sealed in a capped cell, it grows into a worker (female) bee, emerging on the 20th day. Workers do everything but lay eggs and mate. They build the comb from wax extruded from glands under their abdomen. They clean, defend, & repair the hive. They feed the larva, the queen, and the drones. They gather nectar, pollen, water, and propolis. They ventilate, cool & heat the hive.