Garden Wildlife
             Garden Wildlife
Bumblebees

By Andrew Halstead  reviewed by Andrew Salisbury edited by Steve Head


Bumblebees are the largest bees that will be seen in gardens, where they gather nectar and pollen from a wide range of flowers.

Species in Britain and Ireland
There are 27 bumblebee species in Britain and Ireland.  Some species have declined markedly in distribution and abundance over the last 50 years.  These species appear to require wildflowers associated with old flower-rich meadows, which is a habitat that has become much reduced and fragmented over that period.  Bumblebee species that forage on a wider range of flowers, including garden plants, continue to do well and often occur throughout the British Isles.

Common species likely to be seen in gardens are Buff-tailed bumblebee, Bombus terrestris; White-tailed bumblebee, Bombus lucorum; Red-tailed bumblebee, Bombus lapidarius; Early bumblebee, Bombus pratorum; Common carder bumblebee, Bombus pascuorum; Garden bumblebee, Bombus hortorum; Southern cuckoo bumblebee, Bombus vestalis; Wood cuckoo bumblebee, Bombus sylvestris; Field cuckoo bumblebee, Bombus campestris; Tree bumblebee, Bombus hypnorum.  The last mentioned is a European species that has recently colonised Britain without human assistance,being first recorded in Wiltshire in 2001.  It has since become widespread in England and Wales, and is spreading in Scotland.   Jennifer Owen caught over 9,300 bumblebee individuals, from 13 species, with the Comnon carder bumblebee much the most abundant.






In mid to late summer, the bumblebee colony reaches peak strength and may contain up to about 100 adult bees.  At that time, if the colony is strong enough, the queen will lay some eggs that have not been fertilised.  The larvae from these eggs will become male bumblebees.  Some of the larvae from fertilised eggs will be given extra food and this enables the resulting adult bees to be queens with functioning ovaries.  Mating takes place in late summer, so the overwintered young queens are ready to start reproducing in the following spring.  In late summer, the old queen, the workers and the males die, while the young queens burrow into the soil where they overwinter.  Common carder bumblebee nests are usually the last to die out, with workers still active in October.

Cuckoo bumblebees do not produce a worker caste.  All of their eggs will develop as larvae that become young queens or males.  They do not need worker bumblebees of their own as they exploit those of the host bumblebee species to provide food for the larvae.

In recent years, some queens of some bumblebees, particularly the Buff-tailed bumblebee, have not remained dormant over the winter.  They have emerged in winter and have established nests to the extent that some worker bumblebees can be seen collecting nectar and pollen from winter-flowering garden plants, such as Clematis cirrhosa and Mahonia species.  It is doubtful if these winter colonies can survive long enough to rear queens and males.  The appearance of winter bumblebee colonies in Britain may be an indication of milder winters resulting from climate change. 

Role of bumblebees in gardens
Bumblebees are useful pollinating insects.  Although often less numerous than honeybees, bumblebees are more tolerant of cold wet conditions and will visit flowers when honeybees stay in their hives. Colonies of the Buff-tailed bumblebee can be purchased and are used by commercial growers to pollinate glasshouse crops, such as tomatoes and peppers.  

Bumblebee tongues are formed from the labium, supported by the maxillae, and vary in length. Some species are adapted with long tongues to take nectar from deep flowers such as lavender. the Garden bumblebee Bombus hortorum's tongue is twice as long as that of Bombus terrestris.  Bumblebee species with short tongues sometimes cheat in order to get at nectar that cannot be reached from the front of the flower.  They bite a hole in the base of the flower, which gives them access to the nectar without coming into contact with the pollen-bearing anthers, thus reducing the chances of pollination occurring.  Holes made in the base of flowers are often seen on runner bean, broad bean and aquilegia.

Bumblebee nest boxes can be bought from garden centres but they have a notoriously poor success rate in attracting a queen bumblebee in the spring.  Queens seem to prefer to find their own, more natural, nest sites.  Worker bumblebees can sting but they are generally not aggressive and rarely use their stings unless they are handled clumsily or their nest is under attack.  Tree bumblebees are more likely to chase people and sometimes sting them. This is mainly a problem where they are nesting in a bird box which has been placed where people will walk close by. 

Other sources of information

Websites
Website of the Bumblebee Conservation Trust
Website of the Bees, Wasps and Ants Recording Society (BWARS)
Images and information by Steve Falk

Books
Benton, T. (2006) Bumblebees. Collins New Naturalist series no. 98. Harper Collins
Edwards, M. & Jenner, J. (2009) Field Guide to the Bumblebees of Great Britain and Ireland.  Ocelli Ltd
Goulson, D. (2010) Bumblebees, Behaviour, Ecology and Conservation.  Oxford University Press
Kirk, W. D. J. & Howes, F. N. (2012) Plants for Bees. International Bee Research Association
Prys-Jones, P. E. & Corbet, S. A (2011) Naturalists' Handbooks 6 Bumblebees. Pelagic Publishing



Bumblebees

By Andrew Halstead  reviewed by Andrew Salisbury edited by Steve Head

Bumblebees are the largest bees that will be seen in gardens, where they gather nectar and pollen from a wide range of flowers.

Species in Britain and Ireland
There are 27 bumblebee species in Britain and Ireland.  Some species have declined markedly in distribution and abundance over the last 50 years.  These species appear to require wildflowers associated with old flower-rich meadows, which is a habitat that has become much reduced and fragmented over that period.  Bumblebee species that forage on a wider range of flowers, including garden plants, continue to do well and often occur throughout the British Isles.

Common species likely to be seen in gardens are Buff-tailed bumblebee, Bombus terrestris; White-tailed bumblebee, Bombus lucorum; Red-tailed bumblebee, Bombus lapidarius; Early bumblebee, Bombus pratorum; Common carder bumblebee, Bombus pascuorum; Garden bumblebee, Bombus hortorum; Southern cuckoo bumblebee, Bombus vestalis; Wood cuckoo bumblebee, Bombus sylvestris; Field cuckoo bumblebee, Bombus campestris; Tree bumblebee, Bombus hypnorum.  The last mentioned is a European species that has recently colonised Britain without human assistance,being first recorded in Wiltshire in 2001.  It has since become widespread in England and Wales, and is spreading in Scotland.   Jennifer Owen caught over 9,300 bumblebee individuals, from 13 species, with the Comnon carder bumblebee much the most abundant.



Biology
Bumblebees are social insects but, unlike honeybees, bumblebee colonies die out in late summer-early autumn and do not persist overwinter.  Only young queen bumblebees survive the winter.  They bury themselves in the soil and emerge in spring.  For most bumblebees, an ideal potential nest site is an abandoned tunnel in the soil made by a small rodent (eg Mrs Tittlemouse).  A location such as this may contain some nest material left by the mouse or vole that will provide insulation for the nest started by the queen.  Bumblebee nests are often located in the sides of ditches and banks, in hedge bottoms and compost heaps.  The Tree bumblebee often nests in bird nest boxes and cavities in trees.  The Common carder bumblebee makes its nests on the soil surface, often in the base of grass tussocks.

Six of the 27 bumblebee species found in the British Isles are cuckoo bumblebees.  Queens of these species are unable to found their own colonies.  They become active later in the spring than other bumblebee queens.  They seek out and enter an established nest of another bumblebee species.  The cuckoo bumblebee queen kills the other queen that founded the nest and takes over, using the worker bumblebees of the host colony to rear larvae of the cuckoo bumblebee.  The Wood cuckoo bumblebee invades the nests of the Early bumblebee; the Field cuckoo bumblebee goes into nests of the Common carder bumblebee; the Southern cuckoo bumblebee goes into nests of the Buff-tailed bumblebee.

Life cycle
When a queen bumblebee has selected a suitable nest site, she secretes some wax that will form a pouch where she will lay a small batch of eggs.  Although bumblebees are social insects, initially the queen is on her own and she has to forage for nectar and pollen, as well as constructing the nest and raising the first brood of larvae.  In spring and early summer, the queen lays fertilised eggs that will become infertile females, known as worker bumblebees.  The larvae are fed by the queen until they are fully grown and ready to pupate.  Once adult worker bumblebees have been raised, they can take over the tasks of foraging and rearing the larvae, leaving the queen to concentrate on egg laying. Worker bumblebees produced during the early stage of colony development are much smaller than those produced in mid summer, when there is more food available for the larvae.

In mid to late summer, the bumblebee colony reaches peak strength and may contain up to about 100 adult bees.  At that time, if the colony is strong enough, the queen will lay some eggs that have not been fertilised.  The larvae from these eggs will become male bumblebees.  Some of the larvae from fertilised eggs will be given extra food and this enables the resulting adult bees to be queens with functioning ovaries.  Mating takes place in late summer, so the overwintered young queens are ready to start reproducing in the following spring.  In late summer, the old queen, the workers and the males die, while the young queens burrow into the soil where they overwinter.  Common carder bumblebee nests are usually the last to die out, with workers still active in October.

Cuckoo bumblebees do not produce a worker caste.  All of their eggs will develop as larvae that become young queens or males.  They do not need worker bumblebees of their own as they exploit those of the host bumblebee species to provide food for the larvae.



Top left: Buff-tailed bumblebee Bombus terrestris   Top right:  Red-tailed bumblebee Bombus lapidarius

Bottom Left:  Cuckoo bumblebees (probably B.vestalis)   Bottom right:  Tree bumblebee Bombus hypnorum
Double click to edit
Top left: Buff-tailed bumblebee Bombus terrestris   Top right:  Red-tailed bumblebee Bombus lapidarius

Bottom Left:  Cuckoo bumblebees (probably B.vestalis)   Bottom right:  Tree bumblebee Bombus hypnorum

Biology
Bumblebees are social insects but, unlike honeybees, bumblebee colonies die out in late summer-early autumn and do not persist overwinter.  Only young queen bumblebees survive the winter.  They bury themselves in the soil and emerge in spring.  For most bumblebees, an ideal potential nest site is an abandoned tunnel in the soil made by a small rodent (eg Mrs Tittlemouse).  A location such as this may contain some nest material left by the mouse or vole that will provide insulation for the nest started by the queen.  Bumblebee nests are often located in the sides of ditches and banks, in hedge bottoms and compost heaps.  The Tree bumblebee often nests in bird nest boxes and cavities in trees.  The Common carder bumblebee makes its nests on the soil surface, often in the base of grass tussocks.

Six of the 27 bumblebee species found in the British Isles are cuckoo bumblebees.  Queens of these species are unable to found their own colonies.  They become active later in the spring than other bumblebee queens.  They seek out and enter an established nest of another bumblebee species.  The cuckoo bumblebee queen kills the other queen that founded the nest and takes over, using the worker bumblebees of the host colony to rear larvae of the cuckoo bumblebee.  The Wood cuckoo bumblebee invades the nests of the Early bumblebee; the Field cuckoo bumblebee goes into nests of the Common carder bumblebee; the Southern cuckoo bumblebee goes into nests of the Buff-tailed bumblebee.

Life cycle
When a queen bumblebee has selected a suitable nest site, she secretes some wax that will form a pouch where she will lay a small batch of eggs.  Although bumblebees are social insects, initially the queen is on her own and she has to forage for nectar and pollen, as well as constructing the nest and raising the first brood of larvae.  In spring and early summer, the queen lays fertilised eggs that will become infertile females, known as worker bumblebees.  The larvae are fed by the queen until they are fully grown and ready to pupate.  Once adult worker bumblebees have been raised, they can take over the tasks of foraging and rearing the larvae, leaving the queen to concentrate on egg laying. Worker bumblebees produced during the early stage of colony development are much smaller than those produced in mid summer, when there is more food available for the larvae.
Bumble bees make wax cells in which to rise eggs and larvae, and to store honey.  Unlike the Honey bee which build combs of identical hexagonal cells, bumblebees make rather less neat wax "pots", as you can see in this photo of the nest of a European bumble bee, Bombus confusus.
In recent years, some queens of some bumblebees, particularly the Buff-tailed bumblebee, have not remained dormant over the winter.  They have emerged in winter and have established nests to the extent that some worker bumblebees can be seen collecting nectar and pollen from winter-flowering garden plants, such as Clematis cirrhosa and Mahonia species.  It is doubtful if these winter colonies can survive long enough to rear queens and males.  The appearance of winter bumblebee colonies in Britain may be an indication of milder winters resulting from climate change. 

Role of bumblebees in gardens
Bumblebees are useful pollinating insects.  Although often less numerous than honeybees, bumblebees are more tolerant of cold wet conditions and will visit flowers when honeybees stay in their hives. Colonies of the Buff-tailed bumblebee can be purchased and are used by commercial growers to pollinate glasshouse crops, such as tomatoes and peppers.  

Bumblebee tongues are formed from the labium, supported by the maxillae, and vary in length. Some species are adapted with long tongues to take nectar from deep flowers such as lavender. the Garden bumblebee Bombus hortorum's tongue is twice as long as that of Bombus terrestris.  Bumblebee species with short tongues sometimes cheat in order to get at nectar that cannot be reached from the front of the flower.  They bite a hole in the base of the flower, which gives them access to the nectar without coming into contact with the pollen-bearing anthers, thus reducing the chances of pollination occurring.  Holes made in the base of flowers are often seen on runner bean, broad bean and aquilegia.

Bumblebee nest boxes can be bought from garden centres but they have a notoriously poor success rate in attracting a queen bumblebee in the spring.  Queens seem to prefer to find their own, more natural, nest sites.  Worker bumblebees can sting but they are generally not aggressive and rarely use their stings unless they are handled clumsily or their nest is under attack.  Tree bumblebees are more likely to chase people and sometimes sting them. This is mainly a problem where they are nesting in a bird box which has been placed where people will walk close by. 

Other sources of information

Websites
Website of the Bumblebee Conservation Trust
Website of the Bees, Wasps and Ants Recording Society (BWARS)
Images and information by Steve Falk

Books
Benton, T. (2006) Bumblebees. Collins New Naturalist series no. 98. Harper Collins
Edwards, M. & Jenner, J. (2009) Field Guide to the Bumblebees of Great Britain and Ireland.  Ocelli Ltd
Goulson, D. (2010) Bumblebees, Behaviour, Ecology and Conservation.  Oxford University Press
Kirk, W. D. J. & Howes, F. N. (2012) Plants for Bees. International Bee Research Association
Prys-Jones, P. E. & Corbet, S. A (2011) Naturalists' Handbooks 6 Bumblebees. Pelagic Publishing

Bumble bees make wax cells in which to rise eggs and larvae, and to store honey.  Unlike the Honey bee which build combs of identical hexagonal cells, bumblebees make rather less neat wax "pots", as you can see in this photo of the nest of a European bumble bee, Bombus confusus.