Why Do Bees Make Honey?

Nectar is mostly water, typically seventy to eighty percent, and sugary water ferments and spoils quickly. It would be useless as a winter store.

Honey is the same sugars with the water driven down to below about eighteen percent. At that concentration it is too dry for microbes to grow in, so it keeps almost indefinitely. The colony is essentially running a preservation process.

Foraging bees collect nectar in a specialised stomach and return to the hive, where it is passed mouth to mouth between workers. During this the bees add enzymes, notably invertase, which splits complex sucrose into simpler glucose and fructose.

Another enzyme, glucose oxidase, produces small amounts of hydrogen peroxide and gluconic acid, making the honey acidic and mildly antiseptic. The nectar is then deposited into cells and the bees fan it with their wings to evaporate water. When it is dry enough, they cap the cell with wax.

The numbers are striking. A single worker bee produces about a twelfth of a teaspoon of honey in her entire life, and a jar represents the combined effort of thousands of bees visiting millions of flowers.

A strong colony may produce far more honey than it needs in a good year, which is what makes beekeeping possible. Responsible beekeepers take the surplus and leave enough for the colony, or feed sugar syrup back if they take too much.

Several properties combine to make honey remarkably stable:

• •Very low water content, so microbes cannot grow
• •High sugar concentration, which draws water out of any cells present
• •Acidity from gluconic acid, around pH 3.9
• •Traces of hydrogen peroxide released slowly from enzymes

Honey is only one product. Bees also collect pollen for protein, produce wax from glands on their abdomen for comb, and make propolis from plant resins to seal gaps and sterilise surfaces.

Worth noting: honey should never be given to infants under one year, because it can contain botulism spores that a developing gut cannot handle. It is harmless to older children and adults, whose gut flora outcompete the spores easily.

Honeybee colony losses and wild pollinator declines have been widely reported, and the causes are generally agreed to be multiple rather than singular: habitat loss, pesticide exposure, parasitic varroa mites, disease and changing climate.

The consequence is not mainly about honey. Around three quarters of leading global food crops benefit to some degree from animal pollination, including most fruits, nuts and many vegetables. Staple grains are wind pollinated and would be largely unaffected, so the risk is to dietary variety and nutrition rather than to calories.

A jar of runny honey that turns thick and grainy has not spoiled. Honey holds more dissolved sugar than water can normally keep in solution, so it is supersaturated. Over time, glucose, which is less soluble than fructose, begins to form crystals. Honey from flowers rich in glucose, such as oilseed rape, can set within weeks, while honeys with more fructose, such as acacia honey, may stay liquid for a long time. Cool storage speeds crystallisation, which is why honey often sets faster in a cold kitchen.

You can return crystallised honey to liquid by standing the jar in warm water and stirring gently. Strong heating is best avoided, because it can darken the honey, dull its aroma and damage the enzymes the bees added. Some producers deliberately encourage fine crystals to make set or creamed honey, which spreads smoothly. The real enemy of stored honey is moisture. Honey absorbs water from damp air, and if its water content rises enough, yeasts can begin to ferment it, so jars should be kept closed.

A honeybee that finds a rich patch of flowers can share its location using the waggle dance, decoded by the Austrian scientist Karl von Frisch, who shared a Nobel Prize in 1973. On the vertical comb inside the dark hive, the forager runs a short straight line while waggling her body, then loops back and repeats. The angle of the waggle run compared with straight up shows the direction of the food compared with the direction of the Sun. The length of the waggle run indicates distance, with longer runs meaning farther flowers.

Other bees follow the dancer closely, picking up the movements through touch and vibration, as well as the scent of the flowers on her body. For food very close to the hive, bees use a simpler round dance that signals nearby food without precise direction. The dance even accounts for the Sun's movement across the sky, as dancers adjust the angle over time. This sharing system lets a colony send many workers to the best sources quickly, which is a large part of how it gathers enough nectar to make its stores.

When the weather turns cold, a honeybee colony gathers into a tight winter cluster on its combs. Bees in the middle generate heat by shivering their flight muscles without moving their wings, burning honey as fuel. Bees on the outside pack closely together to form an insulating layer, and individuals swap between the cooler surface and the warm centre over time. The outer layer is allowed to cool, but not too far, because a honeybee chilled to around ten degrees Celsius can no longer work its muscles properly and cannot rewarm itself.

The bees doing this work are different from summer workers. Summer foragers live only a few weeks, worn out by constant flying, but winter bees, raised in late summer and autumn, can survive for several months. Drones, the males, are usually driven out of the hive in autumn, so they do not eat into the stores. The cluster moves slowly across the combs, consuming the honey around it. In a cold climate a colony may need tens of kilograms over winter, and on mild days bees leave briefly on cleansing flights, because they avoid emptying their bowels inside the hive.

Honey is one of the foods most often faked, usually by diluting it with cheaper sugar syrups, so laboratories have developed ways to test it. One method looks at pollen. Each honey contains pollen grains from the flowers the bees visited, and experts can identify them under a microscope, checking whether a jar labelled as lime blossom or from a particular country really matches its claim. Another method uses carbon isotopes. Plants such as maize and sugar cane fix carbon in a slightly different way from most nectar plants, leaving a distinctive ratio of carbon atoms that shows up when syrups made from them are added.

Fraudsters responded by switching to syrups made from rice or beet, which share the carbon signature of most nectar plants, so newer tests look for traces of particular sugars and use detailed chemical fingerprints. Manuka honey raises a different problem. Made from the nectar of a shrub native to New Zealand and Australia, it contains unusually high levels of a compound called methylglyoxal, which forms as a substance from the nectar slowly converts while the honey matures. Because manuka sells for a high price, its labels often quote a methylglyoxal grade, and New Zealand has set a scientific definition combining chemical markers with a DNA test for manuka pollen.

Bees make honey as a preserved winter food store, converting watery nectar into a dry, acidic, enzyme treated sugar concentrate that microbes cannot spoil, which is why sealed honey lasts effectively forever.