How Do Bees Make Honey?

What does a forager bee do with nectar?

Worker honey bees divide up their jobs, and the ones called foragers fly out to flowering plants to collect nectar.^[1] Bees prefer to forage close to home, ideally within 300 feet of the hive, but they will fly up to five miles if they need to.^[8] A forager drinks the nectar and stores it in her crop, an internal pouch also known as the honey stomach.^[1]

Nectar consists mostly of water and sucrose, the sugar sold as table sugar, and water usually makes up about 70 percent of it.^[1] The color and flavor of the finished honey vary with the nectar the bees collect.^[5]

Drying can begin before the forager gets home: researchers who caught bees foraging in macadamia orchards found that the nectar in their crops had about twice the sugar concentration of the nectar in the flowers, with up to 75 percent of the original water already gone.^[2] They concluded that the only way the water could have left was by evaporating from the bee's mouthparts.^[2]

How does nectar turn into honey inside the hive?

Back at the hive, the forager passes her load to other workers by regurgitating it straight into their crops, a food transfer called trophallaxis.^[1][2] Sources give these hive bees different names: processor bees, receiver bees or storer bees.^[1][2][3] A processor bee carries the nectar to the honeycomb, which tends to be near the top of the hive, and deposits it in a six-sided wax cell.^[1] It takes many loads to fill one cell.^[1]

Turning nectar into honey involves both a chemical change and a physical one.^[2]

The chemical change comes from enzymes that bees add to the nectar in the crop while they collect and process it.^[2] NC State University names the enzyme invertase, which splits sucrose into two simpler sugars, glucose and fructose, and says processor bees add it every time they bring the nectar back up.^[1] A 2016 study describes these sugar-splitting enzymes as coming from the workers' hypopharyngeal glands.^[3] The international Codex Alimentarius standard describes the end product as made up mainly of fructose and glucose.^[4]

The physical change is the removal of water, which bees first do actively, repeatedly bringing nectar droplets up onto the tongue and swallowing them again, a behavior known as tongue lashing.^[2] Drying then continues passively from droplets placed in cells, helped by large numbers of bees fanning their wings.^[2] The fanning moves air around the honeycomb so that water evaporates.^[1]

The 2016 study used computer tomography to follow the sugar concentration inside comb cells, in hives given sugar water during a nectar shortage.^[3] It found that bees moved the contents of many cells before final storage as part of ripening.^[3] Earlier studies cited by its authors put ripening at 1 to 11 days, but in their own hives capping was first seen on day 12.^[3] The time depends on conditions such as colony size, the number of available cells, the movement and humidity of air in the hive, the weather and the sugar content of the nectar.^[3]

How much water is left in finished honey?

Bees collect nectar with a sugar content of 20 to 60 percent by weight and must concentrate it to more than 80 percent before they store it.^[2] Sources set the water limit in slightly different places: NC State's explainer says that by definition honey contains less than 18.6 percent water.^[1] The international Codex Alimentarius honey standard, in its 2001 revision, allows not more than 20 percent water in most honeys and not more than 23 percent in heather honey.^[4]

When the honey is ripe, the bees seal its cell with an airtight wax cap.^[1] Timing matters, because concentrated nectar can absorb water from the air in the hive, which can lead to fermentation.^[3] The tomography study found that the last stage of ripening was still under way after capping had begun, which the authors read as a race against water absorption.^[3] Ripe honey contains so little water that microbes cannot grow in it, but a cap that is not airtight lets it absorb moisture and leaves it open to bacteria and fungi.^[1] When beekeepers harvest honey, they scrape off these wax caps before spinning the honey out of the comb.^[5]

Why do bees make honey?

Bees collect nectar as a source of carbohydrates for adults and larvae alike, while pollen provides protein and fat.^[6] According to the National Honey Board, honey gives bees energy for their flight muscles and is used to heat the hive in winter.^[5] Stored honey carries a colony through times when foraging is impossible, such as spells of bad weather or winter in temperate regions.^[3]

Unlike most social insects, honey bees survive winter by clustering together and generating heat, which they do by eating the honey they stored in summer.^[6] A Penn State entomology report describes a winter cluster of several thousand female winter bees and the queen, who vibrate their flight muscles to keep the colony above 85°F even when it is below freezing outside.^[7]

The National Honey Board says honey bees make more honey than the colony needs, so beekeepers harvest the excess, and that an average hive produces about 55 pounds of surplus honey a year.^[5]

How much work does it take to make honey?

A University of Florida extension guide gives a rough figure: honey bees must visit an estimated two million flowers to make one pound of honey.^[8]

Drying nectar also takes a lot of energy: the macadamia researchers cite a modelling study by Mitchell that found the process surprisingly energy-intensive, using up 25 to 60 percent of the sugar in the nectar.^[2] They calculated that drying nectar on the way home saves, on average, 35 times more energy in later honey processing than it saves in flight costs from carrying a lighter load.^[2]