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Bumblebees among the trees

In spring, when meadows and grasslands are yet to fully flower, bumblebees will seek out flowering trees for their pollen. Jamie Buxton-Gould, Project Officer West Country Buzz, tells us more about the importance of flowering trees in spring.

Bumblebees can be pretty easy to watch. Busily feeding on a flower in a park or garden, we can get a close look at their furry bodies, big eyes and whirring wings. But it’s common to hear bumblebees without seeing them, particularly as they feed on some of their favourite spring forage, metres overhead in the branches of trees.

Flowering trees

When thinking of a bumblebee’s favourite plants, trees rarely come to mind. But some of our flowering trees can be popular dishes on the bumblebee menu early in the year.

Some of our hedgerow favourites are among these flowering trees. If they are managed well and not cut every year, they can provide for a multitude of pollinators, including bumblebees:

  • The beautiful white flowers of blackthorn can transform a dense, spiny hedge into a gleaming cloud of blossom in early spring
  • Hawthorn follows later, once it has unfurled some leaves alongside its flowers
  • Field maple and sycamore also attract lots of bumblebees with their sweet nectar

Goat willow

As spring unfolds, goat willow (also known as pussy willow) is one of the top providers of nectar and pollen for bumblebees. Growing more than ten metres high, this tree can spread its branches wide, creating a candelabra of catkins. Starting as soft, furry buds of silver, the catkins have evolved to keep the flowers inside to protect them from harsh winter weather. The warmth of spring encourages them to burst open, revealing their gender.

Trees with golden, fluffy catkins are male. They hold pollen-dusted stamens and a little bit of nectar. The female trees hold a heart-shaped stigma atop a sweet supply of nectar. They will be buzzing with bumblebees on a fine spring day.

Willows, along with oak trees, also support some of the highest diversity of invertebrate, meaning they are essential to encourage in the landscape to support our wildlife.

Queen bumblebees in spring

Spring is a crucial time of year for queen bumblebees. They need to refuel on sugary nectar to top up their energy levels and find protein-rich pollen. This pollen is important to help the queen’s ovaries to develop so she is ready for laying eggs. A queen needs to collect enough pollen for herself and to make a food-store for the next generation of young bumblebees.

Cosy and warm in her new nest, the queen lays her eggs on top of a ball of pollen and broods them to keep them warm – as warm as 25°C. When the eggs hatch, the larvae, which resemble small grubs, feasts on the pollen for ten to twenty days. Afterwards, they spin a cocoon and pupate, like a butterfly.

The fully formed adult bumblebees emerge after two weeks. They help the queen raise the next batch of eggs until the nest reaches a few hundred workers by summer.

Why flowering trees are important in spring

Bumblebee species like the Buff-tailed (Bombus terrestris), White-tailed (Bombus lucorum) and Early bumblebee (Bombus pratorum) have the highest number of queens active in spring. It is often too early in the season for our meadows and grasslands to have many flowers, so flowering trees have an important role to play from March to May.

Apples, cherries, pears and plums provide beautiful blossoms beloved by bumblebees. There are an array of varieties in bloom throughout the spring. Many different species of solitary bee, including Ashy mining bees and Red mason bees, are also important pollinators of fruit trees.

How you can help

If you have space, why not help the bumblebees in your local area by planting a fruit tree and encouraging your friends and neighbours to do the same? If you have a small garden or patio, it is possible to buy dwarf varieties that are happy in a pot and will still produce big, juicy fruits to feed your local bumblebees.