St Nicks

Centre for nature and green living

Spotlight on: Bumblebees in spring

Bumblebee species

Nothing quite confirms the arrival of spring like the first bumblebee sighting of the year as they emerge from hibernation. The low hum of their wings as they zoom past is always a comforting sign that nature is buzzing back to life after those quiet winter months. Wind back 6 months or so to the end of summer when floral resources are dwindling and temperatures are dropping. The new queens produced that year have mated and the time has come to find a sheltered spot to hibernate (the workers, males and old queens gradually die off). They will usually choose somewhere well-drained and north facing and will dig down to a depth of about 10cm (no mean feat for an insect!) to escape from frost and to avoid being awoken prematurely on warm winter days.

Common carder bee nest

Common carder bee nest found in meadow grass

With the arrival of spring, these new bumblebee queens gradually venture out, refueling on nectar and pollen from early spring flowers such as pussy willow, lungwort and gorse to regain their strength ready to build a nest and lay their eggs.  To do this, they must first find a suitable nest site, flying low to the ground, zigzagging to and fro to investigate any potential holes or dry dark cavities. Finding a sheltered spot is important because too much exposure to the sun can cause the nest to overheat and the furry bumblebee doesn’t cope well in very hot temperatures! Most bumblebee species tend to nest underground, using old small mammal burrows or under sheds. Other species nest above ground: the common carder bee for example, uses the hairs on its legs to comb together grass and moss to make their nest (similar to ‘carding’ wool). One of the newest bumblebee species to the UK, the tree bumblebee, nests (as its name suggests) in trees using old hollows or even bird boxes.

Once the new queen has found her nest site, she will lay her first batch of eggs into a ball of pollen which acts as a food source for the newly hatched larvae. She also stores nectar in a wax pot so that she can feed herself while incubating her eggs. This first batch of young will be workers and will help the queen to expand the colony by looking after subsequent batches of eggs and larvae in addition to foraging for pollen and nectar to feed the growing brood. In summer when the nest is well established, the queen will start to lay unfertilised eggs to produce males – from this point onwards, any fertilised eggs she lays will be raised as queens by feeding the larvae much more food to enable them to develop reproductive systems.

Bumblebee lifecycle

Lifecycle of a bumblebee queen: 1. Queen bumblebees hibernate over winter; 2. Refuelling on pollen and nectar from early spring flowers; 3. Incubating the first batch of eggs in the nest; 4. The nest continues to grow with workers helping to raise young; 5. New bumblebee queens and males mate at the end of summer. (Image source: Bumblebee Conservation Trust)

 

Early spring flowers

Early spring flowers are an important food source for bumblebee queens. Clockwise from top left: snowdrops, lungwort, yellow archangel, comfrey.

The success of a bumblebee nest depends on there being sufficient flowers to forage available nearby throughout the flowering seasons. Some of the early flowering species you will find at St Nicks include carpets of snowdrops, bright yellow gorse flowers (with an unmistakable coconut scent), and higher up in the trees, delicate hazel catkins and soft silvery buds of pussy willow trees – woodlands provide a valuable early source of food. A little later, the range of food available increases as blackthorn, hawthorn and the various fruit trees scattered across the nature reserve burst into blossom. Towards summer the meadow bursts into colour, bringing with it the buzz of many happy foraging pollinators.

 

Since the 1940s, 97% of flower rich habitat such as wildflower meadows has been lost due to intensification of agriculture and loss of habitat associated with a growing human population. Here at St Nicks we have been working to improve wildflower habitat for pollinators, not just on the nature reserve but at various sites across the city as part of our Meadow Keepers project. Restoring wild flower rich habitat such as meadows, or even creating a patch of wildflowers in your garden can play a crucial part in ensuring there is enough flower rich habitat available throughout the year: from when the first species emerge in early spring through to providing enough food for the new queens before going into hibernation.

Bumblebee species

Common UK bumblebee species include (clockwise from top left): buff-tailed bumblebee; white-tailed bumblebee and red-tailed bumblebee; common carder bee; tree bumblebee.

Of the 25 species of bumblebee found in the UK, there are seven species that are commonly found. Known as the ‘big seven’ they have all been recorded at St Nicks. If you want to find out more about identifying bumblebees, the Bumblebee Conservation Trust has some useful ID tips and entomologist Steven Falk has an amazing flickr page with hundreds of photos of different species – a fantastic resource for improving your ID skills.

 

If you would like to get involved with St Nicks Meadow Keepers project and help improve habitat for pollinators (not just bumblebees!) across York then visit the Meadow Keepers project page  or contact our Nature Reserve Manager Jonathan Dent on 01904 411821 or jonathan@stnicks.org.uk to find out more.

17 May 2018 | Categories: Spotlight on... | Tags: Bumblebee, flowers, Meadow Keepers, pollinators, spring