Have you ever wondered how bees make honey? It's a fascinating process that begins with summer flowers and ends in the middle of winter. This blog explains the how and why of honey production.
Honey is a sugary substance produced by honeybees. Humans have valued it for centuries – as a source of sweetness, in medicine and in cosmetics. For bees it's more – it’s life and death.
HONEY STARTS OUT AS NECTAR
The honeybee colony is at its peak in summer. A vast force of foragers is working to gather nectar from flowers. Flowers produce nectar as a reward for visiting pollinators like the honeybee.
Nectar is sugar dissolved in water. It’s mainly sucrose (the same sugar people put in their tea) plus two simpler sugars – glucose and fructose. A colony of bees can visit millions of flowers in a day.
Each bee sucks up nectar with its straw-like mouthparts (proboscis - No.1 in the diagram). They store the nectar in their honey stomach (No. 29 in the diagram).
THE PROCESS OF MAKING HONEY
The amount of sugar in nectar varies from plant to plant. It can be as high as 70% in some species Even in this mixture there’s too much water for the nectar to keep for very long. Just like a sugary drink, it will soon ferment.
As the bee sucks up the nectar, it adds an enzyme. The enzyme breaks down the sugar into glucose and fructose - in the bee’s honey stomach as the bee flies back to the hive.
At the hive, the foraging bee is met by a house bee. The forager passes the nectar to the house bee – a mouth to mouth exchange from one bee to the other.
The house bee adds another enzyme. This enzyme reacts with some of the nectar’s glucose to produce hydrogen peroxide. Hydrogen peroxide helps to destroy bacteria in the nectar.
Alongside this chemical processing, a physical process of evaporation begins.
THE HIVE IS HUMMING
The house bees work to evaporate water from the nectar. They do this in two ways.
Individual bees strop the nectar – they draw up a drop of honey on their proboscis and expose it to the air in the hive before swallowing it again. They do this many times – evaporating water each time until the nectar is even more concentrated..
When it’s concentrated enough, the liquid is placed into individual honeycomb cells. Whole areas of comb are filled with this concentrated mixture. Workers will now fan the combs with their wings to encourage more evaporation – the hive literally hums with their activity.
When the water content is about 18% the nectar has become honey. The honey is now concentrated sugar but it is still liquid. This is possible because of something the bees did right at the start of the process – they added an enzyme to break down sucrose.
The chemical nature of sucrose means that it can’t be superconcentrated.
So, by breaking sucrose down into glucose (and fructose) the bees can produce a much more concentrated solution – which, just like humans use sugar to preserve fruit in jam, will store without fermenting.
The bees will stop fanning the comb. They cap each honey filled cell with a lid of airtight beeswax. This little lid will keep out any moisture. It protects the honey from honeybee feet too.
Honey can last for years like this. Bacteria and yeasts can't grow because of the:
high concentration of sugar
antimicrobial action of hydrogen peroxide
exclusion of air and water
As any honey lover knows, honey is amazing. But why do bees spend so much time and effort making it in the first place?
WHY DO BEES MAKE HONEY?
Honeybees are vegetarians - they only feed on the nectar and pollen from flowering plants. They use the sugar found in nectar to power flight and all their other actions.
Lots of other insect pollinators do this but unlike many others, honeybees don’t hibernate over winter.
Honey is a super concentrated sugar solution. Sugar is packed full of energy. Honey is the honeybee’s energy store.
During late autumn and winter, there is a “skeleton crew” of about 10,000 bees inside the hive. They use honey to keep themselves going during the cold months of winter.
More importantly though, they use honey to generate heat. In the middle of winter, the honeybees begin to prepare for spring. They increase the temperature of their hive from about 25 degrees to 35 degrees centigrade.
This is the temperature they need to raise their young. The bees generate the heat with their own bodies. Amazingly they disconnect their flight muscles to do this.
Then, by flying without moving, they vibrate their muscles to make heat. It takes a massive amount of energy to generate the heat they need. This energy comes from honey.
Honey isn't a by-product - it's a way to store the summer energy of nectar for the winter months when there are no flowers
The queen, who has laid very few eggs over winter, starts to lay eggs now. In the newly warmed up hive, these eggs will develop into new bees. These bees will be ready to start visiting the new flowers that appear in the spring.
A colony needs about 20kg of honey to get it through the winter AND to raise young when there may be snow on the ground. This is an important number for a beekeeper to know.
So, the question “How do bees make honey” is an incredible mixture of chemistry and physics – and teamwork.
For anyone that likes to buy honey, it's a fascinating process to understand. For Harry, the beekeeper, it's something to be admired and accounted for in his beekeeping year. He makes sure his bees have enough honey to get through winter. For the bees, it means survival - a colony ready for another spring.
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Photograph of a honeybee courtesy of Gilles San Martin on Flickr under a Creative Commons Licence
Diagram of the internal anatomy of a honeybee - Bee Anatomy at Ask a Biologist Arizona State University
Information about the chemistry of honey - The Chemistry of Honey by Sharla Riddle at Bee Culture
Information about the composition of nectar - Nectar composition and concentration of 26 species from the temperate forests of South America by Chalcoff, Aizen and Galetto in the Annals of Botany