Most fruit crops require pollination to ensure that fruit sets. Pollen grains get caught on the sticky surface of the stigma, germinate and produce a tube that grows down the style and unites with the female cell in the ovary. This union is called fertilization. After fertilization occurs, seeds develop and the fruit enlarges. Diagram of apple flower.
Honeybees are the most important natural carriers of pollen.
As the bee flies from flowers on one tree to those on another in the orchard, pollen sticks to its body hairs. The bee rubs off the pollen onto the stigma and transfers additional pollen from the anthers as it visits the flowers. A honeybee may visit 5,000 flowers a day. Home plantings of fruit crops generally have enough wild bees for adequate pollination. However, in commercial orchards, beehives are generally placed in the orchard when the trees are in bloom to enhance pollination and fruit set.