When you see bees buzzing around outside, they’re most likely looking for nectar and pollen. Nectar contains sugar and pollen is packed full of protein, so the bees can use these two foods to feed not only themselves but also their young and other members of the colony if they live in a hive. Honey is made by honey bees from nectar, to see them through the winter, when there’s no other food about and it’s too cold to fly. In fact, honey is so good as a winter ‘store cupboard’ food source for bees that it can last almost indefinitely without going off; when archaeologists were excavating ancient Egyptian tombs, they found jars of 3,000-year-old honey that were still perfectly edible.
Solitary bees, on the other hand, don’t make honey and bumblebees only make tiny amounts of a honey-like substance, which they eat themselves. This is because neither solitary bees nor bumblebees are awake during winter – bumblebees either die off or, if it’s a queen bumblebee, she’ll hibernate. Most solitary bee adults also die off before winter comes, leaving young pupae to grow in the nest over the cold months; the new bees emerge in the spring or summer.
The relationship between bees and plants is incredibly complex; in fact, we’re only just beginning to understand how nuanced it is. Both bees and insect-pollinated plants have evolved to benefit each other – over the millions of years that they have depended on each other, bees have developed in different ways to become more effective pollinators, and plants have evolved to become more and more attractive to certain bees.
Some plants, for example, ‘lace’ their nectar with other chemicals, such as caffeine or nicotine, to make them more attractive to bees. Some plants have evolved to look like female bees, so males are tricked into trying to mate with them, pollinating them in the process – a process called pseudo-copulation. And recently, scientists even discovered that some plants make their nectar deliberately sweeter if bees are buzzing close by – evening primrose flowers, for instance, can ‘sense’ when bees are approaching and quickly make their nectar 20 per cent sweeter to try to encourage the insect to land.
Nectar is usually found right at the back of the flower head, so bees have evolved tongues that are really good at reaching this sweet substance and sucking it up. Some bees have short tongues, for shallow flowers, others have long tongues, for deep, tubular-shaped varieties. Some bees are generalists and can drink nectar from a wide variety of plants. Many bees, however, are specialists and have tongues that have evolved to closely match only a certain range of flower: flowers such as honeysuckle or columbine, for example, are too deep for short-tongued bees; equally, long tongues aren’t efficient at working shallow flowers. This makes specialist bees vulnerable to changes in the environment, as they can feed from only a few types of flowers. That’s why planting just one species of flower doesn’t help all kinds of bees.
Some plants make their nectar deliberately sweeter if bees are buzzing close by
We’re also slowly discovering just how varied wild bees’ diet really is. We think we know what kinds of plants bees prefer but they keep surprising us: one fascinating study carried out by bee ecologist Noah Wilson-Rich looked into the plant DNA found in various samples of honey in Provincetown, New England. What he discovered was that much of the honey made in the springtime came from privet, summer honey from water lilies, and autumn honey from sumac – none of these three being plants we immediately associate with bees. He also found just how varied different environments were in terms of plant diversity and bee foraging: honey from rural areas had around 150 different plants species in each sample; honey from suburban areas had far fewer, around 100 plants per sample. And most surprising of all, the city honey had a whopping 200 plant species in each sample – in other words, urban centres were proving to be hugely important for bees and their search for different kinds of flowers. Far from being bad for pollinators, cities may be one of the best places for bees – especially if the suburbs are covered with lawn and rural land is taken up with monoculture farming.
Urban centres were proving to be hugely important for bees and their search for different kinds of flowers
