Today we take honey for granted - it's in every supermarket. But honey is amazing. Beginning with summer flowers and ending in the middle of winter, there's chemistry, physics and teamwork too. This comprehensive blog explains how and why bees make honey.
Honey is the sweet sticky stuff made by honeybees. Long before there was Tate and Lyle, there was honey. Humans have valued it for centuries – as a unique source of sweetness, as a medicine and in cosmetics.
HOW DOES HONEY START OUT
Honey starts out as nectar - which comes from flowers. Nectar is sugar - mainly a sugar called sucrose - dissolved in water. Perhaps surprisingly, this is the same sugar we get from sugar cane and sugar beet today. It's the sugar people put in tea, fizzy drinks and jam.
Sugar is full of energy. Flowers produce energy rich nectar as a reward for visiting pollinators like the honeybee.
READ MORE: What's in a flower and why does it matter?
At its summer peak, a honeybee colony is a vast force of foragers working to gather nectar. They can visit thousands of flowers in a day.
Bees are built for nectar collection. Each bee sucks up nectar with its straw-like mouthparts called the proboscis (No.1 in the diagram). If they don't want to digest it for their own use - to power their flight - they store the nectar in their honey stomach (No. 29 in the diagram). The honey stomach is like a holding tank.
HOW DO BEES TURN NECTAR INTO HONEY - A BIT OF CHEMISTRY
The amount of sugar in nectar varies from species to species. Some can have as much as 70% sugar.
Even at 30% water, there’s way too much water in nectar for it to keep. Just like a sugary drink, it will ferment if kept for too long.
Honeybees have evolved a way to process nectar so that it can keep for ever (almost).
As the bee sucks up the nectar, she adds an enzyme. The enzyme breaks down the sugar into the two simplest sugars - glucose and fructose. This happens in the bee’s honey stomach as she flies back to the hive.
At the hive, the returning bee passes the nectar to one of her sisters - who does some more chemistry. She adds another enzyme. This enzyme reacts with some of the nectar’s glucose to produce hydrogen peroxide.
Just like we use an antiseptic, the hydrogen peroxide helps to destroy bacteria in the nectar - one step on the way to helping it keep.
HOW DO BEES TURN NECTAR INTO HONEY - SOME PHYSICS
The bees inside the hive work to evaporate water from the nectar. They do this in two ways.
Individual bees strop the nectar. They draw up a drop of nectar on their mouthparts and expose it to the air in the hive - before swallowing it again. They do this many times – evaporating water each time - making the nectar more and more concentrated.
When it’s concentrated enough, the bees put the liquid into individual honeycomb cells. Whole areas of comb will be filled with this sugary mixture.
The bees now fan the combs with their wings to encourage more evaporation. They work night and day. If you stand next to a hive in the dark of a summer's evening, the hive literally hums with their activity.
When the water content is about18% 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 into glucose and fructose.
The bees make use of the physical interaction of glucose and fructose, at hive temperature, to produce a concentrated mixture. Through their work, the bees have produced a supersaturated sugar solution - honey.
With so much sugar (82%) things like yeast can't grow - the honey will store without fermenting.
Once they've made their honey, the bees will stop fanning the comb. They cap each honey filled cell with a beeswax lid. Just like a lid on a jar, this little cap will keep out any moisture. It protects the honey from honeybee feet too.
Honey can last for years like this because:
the high concentration of sugar stops yeast growing
hydrogen peroxide has an antimicrobial action - bacteria can't grow
dirt, air and water are kept out
But hang on - honeybees have been around for millions of years. Much as we love it, they don't actually make it for us! Why are they going to all this trouble?
WHY DO BEES MAKE HONEY?
Bees are vegetarians. They only feed on the nectar and pollen from flowering plants. They use the sugar found in nectar to power everything they do.
Like lots of other insect pollinators, honeybees rely on nectar. Unlike most insects, honeybees are active all year round - they don’t hibernate over winter. But from October through to February, there are no flowers - SO, what do the bees eat?
Honey is a super concentrated sugar solution. Sugar is packed full of energy. Honey is the honeybee’s super concentrated energy store.
Honey isn't some handy by-product - it's a way for honeybees to store summer's energy into the winter. It's a matter of life and death!
During late autumn and winter, there is a “skeleton crew” of about 10,000 bees inside the hive. Their job is just to keep the hive ticking over. They cluster together around their queen to protect her. They use their honey to keep themselves going during the cold flowerless months.
More importantly though, they use honey to generate heat.
In the depths of winter, honeybees do something amazing - they start to get ready for spring.
They increase the temperature of their hive from around 25 degrees to about 35 degrees centigrade. This is pretty warm - in fact, it's close to our own mammalian body temperature. This is the temperature they need to raise their young.
The bees generate the heat they need within their own bodies. Amazingly they use their flight muscles to do this.
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.
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 in to new bees.
These bees will be ready to start visiting new flowers as soon as they appear in the spring.
Unlike all the other species of bee, the honeybees's ability to store honey means they haven't needed to hibernate - it's given them a head start.
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.
CONCLUSION
For anyone that likes to buy honey, the how and why of honey-making is fascinating.
For Harry, it's something to be admired and accounted for in his beekeeping year. He makes sure his bees have enough food to get through winter.
For the bees, the answer to the question “How and why do bees make honey” is a serious one. It means a winter survived and a colony ready for another spring. They achieve this with an incredible mix of chemistry and physics – plus some tailor-made biology and a hive full of honeybees working together.
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References:
Diagram of the internal anatomy of a honeybee - Bee Anatomy at Ask a Biologist Arizona State University
Information about the chemistry of honey - The Honeybee Around and About by Celia F. Davis (2019) Beecraft Ltd
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
Thanks to:
Photographs of honeybees courtesy of Gilles San Martin on Flickr under a Creative Commons Licence
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