Honey is a supersaturated sugar solution, composed mainly of carbohydrates – fructose and glucose are usually the main honey sugars – together with water, and small amounts of other compounds, such as organic acids, minerals, vitamins, enzymes, proteins, and amino acids (Machado De-Melo et al., 2018). We all know that honey is good for us, with a wide range of health benefits – particularly its antioxidant and antimicrobial properties – but how do bees make this wonder product?
Of course, the first step in making honey involves gathering nectar. It has been estimated that the honey bees (Apis mellifera L.) from a single hive fly over 15 million km, annually, in order to collect flower nectar and pollen (Southwick and Pimentel, 1981). That’s a phenomenal combined distance; like flying to the moon and back twenty times!
Each individual forager undertakes ten or more excursions from the hive to collect nectar from blossoming flowers on a typical summer’s day; and on such a sunny day, a single honey bee can visit over 1,000 different flowers in the vicinity (within 3 km on average) of their hive. No wonder they are called workers!
As a result of this astonishingly activity, a colony of say, 50,000 bees, can produce up to 125 kg of honey. In order to do this, because the nectar is concentrated to make honey, the bees of one hive need to gather about twice as much of the original flower nectar, say 260 kg. To achive this – each bee only carries about 50mg per trip – a total of about four million foraging trips are made, according to Southwick and Pimentel (1981). Honey bees also collect pollen of course, about 24 kg per hive, with individuals carrying 20 mg per trip, on average. Over a million pollen gathering trips are also made per hive each summer.
Nectar is often quite a dilute solution of sugars – the average nectar concentration of bee-visited flowers is 36% (Wang et al., 2021) – compared to honey, and needs to be concentrated. Bees sometimes concentrate the contents of their crop – a specialised part of their gut also called a honey stomach – by regurgitating it onto their tongue and evaporating the water whilst they are foraging, and on the return flight to the hive. Honeybees also use this technique to cool down: they regurgitate a droplet of nectar onto their proboscis and then withdraw the cooled droplet to achieve evaporative cooling of the head.
The concentration (technically speaking, the osmolality) of honey stored by honeybees needs to be high enough to inhibit microbial growth. This is achieved by hydrolysis of the sugar sucrose, which occurs in nectar, to the monosaccharides glucose and fructose – by the addition of enzymes – and then by a process of evaporation to reach a final concentration of about 82%.
Returning forager bees pass on their nectar loads by trophallaxis to the younger, receiver bees, also called house-bees, or food-handling bees. N.B. Individual bees go through a process of development, starting off by cleaning the nest and feeding the larvae, and only become foragers after about three weeks.
The food-handling bees bees actively evaporate water from the nectar by repeatedly regurgitating and re-ingestimg nectar droplets: a procedure also known as ‘tongue lashing behaviour’ (involving movements of their mouthparts), or bubbling, which was first described by Park in 1925. The nectar is passed from mouth to mouth by the house bees, which digest it for around 30 minutes, adding a special enzyme, called invertase, to catalyze the hydrolysis of the disaccharide sucrose into glucose and fructose.
Further ‘ripening’ of the honey is achieved by passive evaporation, carried out by the fanning behaviour of large numbers of bees circulating air throughout the hive. When the honey is sufficiently concentrated, the bees seal up the honeycomb cells with wax, making them airtight and locking in the honey to be used as food during the winter, or on days when foraging is not possible.
Collective foraging in honey bees is performed by a subset of workers: some forage for nectar, while others forage for pollen. Some bees leave the hive early in the day to scout for new resources, while others leave the hive in response to active recruitment by scouts or other foragers (Lemanski et al., 2019). Honey bees communicate the distance and direction of nectar and pollen sources, by body movements, called waggle dances (something I will explore in another blog as it is such a fascinating subject!😊). Honey bees also collect water in order to regulate the hive temperature in hot conditions.
It turns out that external nectar concentrating behaviour – where bees regurgitate a drop of nectar and then manipulate it with their mouthparts to evaporate off excess liquid – is quite a widespread phenomenon amongst all kinds of different solitary and social bees (Portman et al., 2021). As is bubbling, or bubble blowing in insects in general, as I described in a previous blog about flies blowing bubbles.
Eyer, M., Neumann, P., & Dietemann, V. (2016). A look into the cell: honey storage in honey bees, Apis mellifera. PloS one, 11(8), e0161059.1
Lemanski, N. J., Cook, C. N., Smith, B. H., & Pinter-Wollman, N. (2019). A multiscale review of behavioral variation in collective foraging behavior in honey bees. Insects, 10(11), 370.
Machado De-Melo, A. A., Almeida-Muradian, L. B. D., Sancho, M. T., & Pascual-Maté, A. (2018). Composition and properties of Apis mellifera honey: A review. Journal of apicultural research, 57(1), 5-37.
Mustar, S., & Ibrahim, N. (2022). A sweeter pill to swallow: A review of honey bees and honey as a source of probiotic and prebiotic products. Foods, 11(14), 2102.
Nicolson, S. W., & Human, H. (2008). Bees get a head start on honey production. Biology letters, 4(3), 299-301.
Park, W. (1925). The storing and ripening of honey by honeybees. Journal of Economic Entomology, 18(2), 405-410.
Southwick, E. E., & Pimentel, D. (1981). Energy efficiency of honey production by bees. BioScience, 31(10), 730-732.
Fascinating piece Ray, thank you for this
Thank you for refreshing my knowledge of honey production. A combined annual distance of 15 million km (spent on the beeline, so to speak) is really remarkable. Looking forward to your waggle dance blog. 🐝🔃🧭🌺