How do bees make honey? Here I'll explain the 4 steps to honey production and its surprising impact on our world
This blog describes how bees make honey - including some fascinating details about bee biology plus a little chemistry and physics.
HOW DO BEES MAKE HONEY - STEP BY STEP
Honey has been a unqiue source of sweetness for centuries.
There are thousands of bee species in the world but only honeybees make honey. It's why humans started keeping them in the first place. It's still a valuable human food today.
Honey starts out as nectar - which comes from flowers. It is sugar - mainly a sugar called sucrose - dissolved in water.
Sugar is full of energy. It's this energy that bees want.
Perhaps surprsingly, this is the same sugar we get from sugar cane and sugar beet. It's the sugar people put in tea, fizzy drinks and jam.
The amount of sugar in nectar varies from species to species. Sometimes it's as much as 70%. Even with 30% water there's way too much water for it to keep. Just like a sugary drink, the nectar will ferment if kept too long.
Honeybees have evolved a way to process nectar so that it can keep forever (almost).
At it's simplest, the process of honey production involves:
gathering the nectar
adding enzymes to it
evaporating water from it
storing the finish product in honeycomb
WORKER BEES - THEIR ROLE IN HONEY PRODUCTION
All the work in a hive is done by female worker bees. This includes collecting nectar and turning it into honey.
At its summer peak, a honeybee colony has a vast force of perhaps 30,000 females all working to gather nectar. They can visit thousands of flowers in a day. Beekeepers call this activity foraging.
Bees are built for nectar collection. Each foraging bee sucks up nectar with straw-like mouthparts called the proboscis (No.1 in the diagram).
If they don't want to digest it to power their own flight, they store the nectar in their honey stomach (No. 29 in the diagram).
The honey stomach is a holding tank that allows the bee to transport nectar back to the hive.
STEP 1 - FORAGING FOR NECTAR - THE START OF HONEY PRODUCTION
Foraging honeybees don't randomly visit every flower they come across (like butterflies and flies). They are much more efficient with their time and energy.
Worker bees learn quickly and have excellent memories. A forager rapidly learns the colour and shape of a flower. If it gives a good supply of nectar (or not) she will remember it and visit it repreatedly. This is called flower constancy.
Vision is not the only sense at work. A honeybee has an amazing ability to differentiate and remember scent. Presented with 1,816 scents, honeybees can tell the difference between 1,729 of them.
As she gets closer to the flower, as well as colour, shape and scent, the bee recognises other features:
texture
electrical charge
humidity
temperature
taste
STEP 2 - TURNING NECTAR INTO HONEY USING ENZYMES
Having found the flower she wants, the worker sucks up nectar with her proboscis. As she does so, she adds an enzyme.
The enzyme breaks down the sucrose into two simpler sugars - glucose and fructose. This happens in the bee's honey stomach on her way back to the hive.
At the hive, the returning bee passes the nectar to one of her sisters. This worker, called a receiver bee, adds another enzyme which reacts with the nectar's glucose to produce hydrogen peroxide.
The hydrogen peroxide helps destroy bacteria in the nectar - one step on the way to helping it keep.
The next step is to get rid of all that water.
STEP 3 - TURNING NECTAR INTO HONEY BY EVAPORATION
Individual bees strop the nectar. They draw up a drop of nectar and run it along their mouthparts. They expose it to the air - before swallowing it again. They do this many times - making the nectar more and more concentrated.
But it needs to be even more concentrated. This stage uses the honeycomb itself.
STEP 4 - STORING AND RIPENING HONEY IN HONEYCOMB
Honeycomb is made with wax secreted by the bees themselves. It has many functions including its use in honey production and storage.
When concetrated enough, the bees put the liquid they have been stropping into individual honeycomb cells. In June, July and August whole areas of comb are filled with this sugary mixture.
Evolution has ensured that the bees make cells pointing upwards slightly - so that the still runny mixture doesn't dribble out!
The worker bees fan the combs with their wings to encourage more evaporation. Beekeepers call this ripening the honey. Working night and day, the hive hums with the sound of thousands of beating wings.
When the water content is about18% the nectar has become honey.
With so much sugar (82%) things like yeast can't grow. Unlike nectar, the honey will store in the comb without fermenting.
Finally, the bees seal each honey filled cell with a beeswax cap. Just like a lid on a jar, the cap keeps out moisture and dirt (from lots of honeybee feet).
The bees have used the properties of glucose and fructose, at hive temperature, to produce a concentrated mixture. Through their work, they have produced a supersaturated sugar solution - which we know as honey.
THE BIGGER PICTURE - FORAGING, POLLINATION AND BIODIVERSITY
So far, I've described things from the honeybees' perspective BUT this story has another important player - flowers.
Plants can't move and mate with each other like animals can, so flowering plants use bees (and other pollinators) to move about on their behalf. In his brilliant book "Bees" Christopher O'Toole calls this "mating by proxy".
Nectar is the bribe that flowers offer bees to get them to come and visit.
The bees come foraging for nectar and get covered in pollen. They eat pollen too - but that's another story.
Pollen contains the male genes of a plant. The pollen covered bee carries these genes to another flower of the same species where, hey presto, they meet up with that flower's female genes. The plant has been pollinated (fertilised). It can now make seeds and bear fruit.
READ MORE: What's in a flower and why does it matter?
A honeybee colony produces about 300kg of honey in a season. This takes about 7.5 million flower visits. That's a lot of pollination!
Honeybees are the focus here but there are at least 20,000 other kinds of bees in the world - more than all the species of birds and mammals combined. There are about 270 in the UK alone. Each species has its own special foraging relationship with flowers.
Bees are keystone species - they are essential to the pollination of the flowers, trees and shrubs we see around us. They also pollinate hundreds of our crops.
CONCLUSION
So, after a lot of hard work, honeybees have turned flower nectar into honey. They've done this through an incredible mix of chemistry, physics and teamwork plus some tailor-made biology.
The honey they make can be stored for years because:
It's high sugar concentration stops yeast growing
Hydrogen peroxide has an antimicrobial action - bacteria can't grow
Dirt , air and water are kept out by a beeswax cap
Thats great for the bees and, of course, for us! More importantly, without them and thousands of other bee species, the diverse, productive and colourful world we know today would not exist.
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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
Relevant books about bees:
Bees: A Natural History by Christopher O'Toole, (2013) Firefly Books
The Buzz about Bees : Biology of a Superorganism by Jugen Tautz (2008) Springer
Thanks to:
Photographs of honeybees courtesy of Gilles San Martin on Flickr under a Creative Commons Licence
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