Bumble bees: Identification by Ann Chilcott

No need to bumble through bee identification thanks to some tips from Ann Chilcott, Scottish Expert Beemaster

Body size, colouring, tongue length, nesting requirements and forage sites are different across the range of sub-species of bees so that in order to better help these insects we can gain a basic understanding of these differences and plant a wide range of plants to sustain them. We can also provide and protect nesting sites and generally improve their chances of surviving and proliferating.

Common Carder Bee (Bombus pascuorum) by Nick Wood

Most commonly sighted

A field guide to bumble bees will make much easier identification for you, but for now I will concentrate on the top eight bumble bees that make up around 95-99 per cent of the bees that you will see around your gardens and land depending, of course, on where you live in the UK. These are:

1. Bombus pascuorum or Common Carder-bee

2. Bombus lapidarius or Red-tailed Bumble bee

3. Bombus pratorum or Early Bumble bee

4. Bombus hypnorum or Tree Bumble bee (currently found only in the south east of England)

5. Bombus hortorum or Garden Bumble bee

6. Bombus Jonellus or Heath Bumble bee

7. Bombus terrestris or Buff-tailed Bumble bee

8. Bombus lucorum or White-tailed Bumble bee

Tail colours, Credited to The Bumble bee Conservation Trust

Tail colour

Our list can be broken down into three groups according to tail colour and these are: white tailed including white, off white and yellow; red-tailed and uniform-tailed (of the same colour such as Common Carder-bee).

White-tailed bumble bees include: Tree, Heath, Garden, Buff-tailed and White-tailed Bumble bees.

Red-tailed bumble bees include: Early and Red-tailed Bumble bees.

Uniform-tailed bumble bees include: Common Carder; the rare Moss Carder; and even rarer Great Yellow Bumble bee (Bombus Distinguendus found only in the north and west of Scotland, Orkney and south west Ireland).

Most bumble bee males and females of each sub-species have slightly different markings and even experts are challenged to correctly identify them, especially in summer when hairs become sun-bleached. Relying on photography is difficult since the bees move quickly contorting and bending to reach nectaries and making a full body shot almost impossible. Carrying an ID sheet is useful and you can sketch quickly the colours and banding to help confirm later your first thoughts.

Early Bumble Bee (Bombus pratorum) by Kevin Hill

Tongue length

Having knowledge of tongue lengths is useful when planning to plant for bumble bees whether this be in your garden, orchard, allotment or field. Short-tongued species include: White-tailed, Buff-tailed; Early; Red-tailed; Heath and Tree Bumble bees. The first two can rob nectar from the longer flower tubes but generally these short-tongued bees will forage on the following: white clover; melilot; bird’s foot trefoil and other small flowers in the pea family; harebell; devil’s bit scabious; heat; heather; knapweed; fruit trees and bramble.

The long-tongued bees from our list include the Garden and Common-carder bumble bees and they favour flowers with longer floral tubes such as: foxglove; red clover; dead-nettle; and other mint- family flowers such as mint and thyme; red bartsia; knapweed; woundwort; marsh thistle; vetch; bird’s foot trefoil and other pea family members.

Willow is a wonderful source of pollen when the first queens emerge and assiduously search for protein-rich food to rebuild their body tissues after their long winter hibernation. They need pollen and nectar throughout their season (April-September) and it is more cost effective in time and energy for them to collect from patches of suitable flowers rather than seek single plants. So, if areas of land are planted with a rich variety of flowers that bloom at different times of the year this is far more useful to bees than having a few exotic garden plants available for often cultivated horticultural varieties are so selectively bred that pollen and nectar cannot be accessed by hungry bumble bees.

Generally, bumble bees will fly around 400 metres from their nests for forage and once the queen has established her nest and produced workers, she stays at home whilst the workers collect food. If forage is lost on agricultural land through silage making, topping grass fields, over-grazing by sheep, cattle or horses it can impact negatively on colonies and thus populations. Bumble bee nests are usually small with some having up to 150 workers and others as few as forty.

Threats and predators

Interestingly, bumble bees appear to be immune to plant toxins that harm humans, honey bees and other insects. They can readily metabolise aconite an alkaloid highly poisonous to humans that is found in monk’s hood, Aconitum napellus, and likewise the grayanotoxins from Rhododendron ponticum. This invasive non-native rhododendron flourishes also in Turkey where honey bees make honey from this and in its unripe form is called “mad honey” because, if eaten, in large quantities it can cause hallucinations. In Turkey during 400BC a retreating Greek army of 10,000 soldiers camped in a well-stocked Black Sea coastal village and ate this honey straight from the hives that they found with dramatic consequences. Some behaved as though drunk, but those who ate a lot were out cold for 24 hours and on the fourth day when they could get up they felt as though they had been taking medical purgatives.

Bumble bees are not immune to pests, parasites and diseases and cuckoo bumble bees specialise in usurping the nests of true bumble bees by killing the queen and laying eggs in her nest. They often closely resemble their unwilling hosts but if you look closely at cuckoo bumble bees you will notice that both male and female have hairy legs and the female has no pollen baskets, unlike the true bumble bee female who has smooth pollen baskets. The former has a smaller face than the latter and emerges from hibernation around six weeks after the host species who has done all the hard work nest building and food provisioning that the cuckoo will take over.

An even nastier parasite is the conopid fly that lays an egg inside the bumble bee abdomen so when it hatches it feeds on the abdominal contents and affects bumble bee behaviour causing it to crawl about unable to fly. Intestinal roundworms feed inside bumble bees and external mites cluster around the thorax to scavenge on pollen and nectar. These mites are useful and clear up nest debris too but there are other mites that live inside bumble bee breathing tubes and they are not so benign.

Badgers have a penchant for bumble bee nests which are a good source of protein and they will detect nests by the strong smell digging them up destroying whole colonies. Hedgehogs will also destroy nests in this manner.

Common Carder Bee nest by Raymond Hutcheon

How to help

On a small scale, we can assist bumble bees with safe nesting by leaving areas of garden wild perhaps having piles of stones and wood surrounded by tall grass. Carder bees acquired their moniker from the way they construct their nests by working the fibres of leaf litter and moss so that they are broken up and realigned forming a uniform mix of material. These nests are often found in piles of grass clippings and compost heaps or amongst wild foliage in corners of gardens so these areas may be left undisturbed during the nesting season and cleared up before winter.

There is no current research on the efficacy of artificial nest boxes but no harm can be done by setting up a few in your garden. Encouraging young children to become involved in bumble bee conservation is a rewarding activity that benefits all involved. Hollow- stemmed plants such as Apiacea (carrot) family member angelica (Angelica archangeli) provide both pollen and nectar for insects, and also ideal accommodation when their stems are dried, cut to lengths, tied up in bundles and placed in quiet places around the garden.

Hopefully, having further knowledge and awareness of bumble bees and their habitats will give you more power to improve things for our important pollinators.