Identifying bumblebees

through basic outline drawings 

(illustration showing identification problems arising from absent colouring)


The drawings represent fresh bumblebees with the banding and colours representative of the ‘standard’ bee of each sex. They may appear quite different at later stages of life. For instance, I saw a cuckoo bumblebee on a garden flower in August and the bands were near-white on black, rather than shades of yellow on black and white. However, these present what a freshly-emerged bee ought to look like. The photographs show a variety of stages and represent some of the problems involved in identification from visual sightings.

 

True bumblebees (Bombus)

True bumblebees are, on the whole, covered throughout with hairs, the females have glossy flat rear tibiae with a long fringe of hairs forming the pollens basket; their heads are generally hairy.

Bombus hortorum (Linnaeus 1761)
Common, especially in gardens. Known from its very long face and tongue, as differentiation from similar but short-faced B. jonellus. Lengths: queen 17-22mm, male 13-15mm, worker 11-16mm


Bombus humilis Illiger 1806
Very rare in Somerset. One of the all-brown bumblebees, with brown band at base of abdomen as distinguishing mark. No black hairs on the abdomen, some at wing bases. Lengths: queen 16-18mm, male 12-14mm, worker 9-15mm


Bombus hypnorum (Linnaeus 1758)
Becoming common in gardens. Similar to B. pascuorum, but with a white tip to the tail instead of coloured. A recent arrival which has found local conditions perfect. Lengths: queen 15-20mm, male 14-16mm, worker 8-18mm

     
Bombus jonellus (Kirby 1802)
Not uncommon in heathy, shrubby surrounds, sometimes in gardens. Distinguished from very similar B. hortorum by its short, round head and tongue. Lengths: queen 15-17mm, male 12-14mm, worker 10-14mm


Bombus lapidarius (Linnaeus 1758)
Common in gardens and elsewhere. Queen and worker separated from the much rarer B. ruderarius by having dark hairs on the pollen basket and B. rupestris by the latter’s characteristic cuckoo appearance and bald head. Lengths: queen 20-22mm, male 14-16mm, worker 11-16mm

 

Bombus lucorum (Linnaeus 1761)
Common in gardens and elsewhere. Workers may be tricky to tell from B. terrestris but snow-white tail indicates this species. Lengths: queen 18-21, male 14-16mm, worker 9-17mm


Bombus monticola Smith 1849
Extremely local, on Exmoor. Considerable length of orange-red colour on tail helps identify this bee. Lengths: queen 16-23mm, male 14-15mm, worker 9-16mm


Bombus muscorum (Linnaeus 1758)
Not uncommon in wetlands. Local. Another brown-bodied bee but often very brightly coloured. No black hairs on wing bases or at sides of abdomen. Lengths: queen 17-19mm, male 13-15mm, worker 10-16mm


Bombus pascuorum (Scopoli 1763)
Extremely common in gardens and elsewhere. The main brown-bodied bumblebee, but varies from very bright colouring to absolutely plain. Always some black hairs on the side of the abdomen. Lengths: queen15-18mm, male 12-14mm, worker 9-15mm


Bombus pratorum (Linnaeus 1761)
Usually very common but it can vary year to year. Small and lively. Lengths: queen 15-17mm, male 11-13mm, worker 10-14mm


Bombus ruderarius (Müller 1776)
Uncommon and local in heathland surrounds. Short, wide orange-red tail. Similarly-coloured hairs on pollen baskets of queens and workers distinguish this bee from females of B. lapidarius which have black hairs. Lengths: queen 16-18mm, male 12-14mm, worker 9-16mm


Bombus ruderatus (Fabricius 1775)
Probably local and uncommon, but only recently have keys been produced which distinguish it from B. hortorum, but really only on dead specimens, so current position can be said to be unknown. Lengths: queen 21-24mm, male 15-17mm, worker 11-18mm
  
Bombus soroeensis (Fabricius 1777)
Local and rare. Broken band on middle of abdomen is characteristic. This appearance can appear on other species as a temporary aberration while feeding but if it remains, this is the characteristic factor. Lengths: queen 15-17mm, male12-14mm, worker 10-14mm


Bombus sylvarum (Linnaeus 1761)
A few years ago, it was relatively common in parts of the Levels but has once again suffered a drastic reduction. Generally, known as a very local rarity. The subject of much research in Somerset over the past ten years or so. Characterised by the black-haired band between the wings and a very high-pitched note in flight. Lengths: queen 16-18mm, male 12-14mm, worker 10-15mm


Bombus terrestris (Linnaeus 1758)
Common in gardens in particular. Difficult to distinguish between B. lucorum workers and this species, though a degree of colouring on the white of the tail generally makes it B. terrestris. Lengths: queen 20-23mm, male 14-16mm, worker 11-17mm
 
Cuckoo bumblebees (Formerly Psithyrus)

Cuckoo bumblebees have a deal of dark body chitin showing through sparse hairs, particularly on the abdomen, giving a glossy, banded appearance; the females have matt rounded  rear tibiae and clearly do not have a full surround of stiff hairs. Their wings are dark and they have rounded, often near-bald, shiny heads.

Bombus barbutellus (Kirby 1802)
A cuckoo on B. hortorum, but not as numerous as its host. In common with B. bohemicus, this species appears to rapidly change its appearance from the immaculate colours shown in books. They quickly fade to grey or silver in place of the yellow making identification difficult. Lengths: female 17-19mm, male 15-16.5mm


Bombus bohemicus (Seidl 1837)
Cuckoo on B. lucorum. Much less common and difficult to distinguish from the similar B. vestalis.  The colouring overlaps and the key difference, the comparative antennal segments are not that certain. See remarks above also. Lengths: female 18-25mm, male 15-18mm

 
Bombus campestris (Panzer 1801)
Cuckoo on B. pascuorum and is said perhaps to parasitise the other brown bumblebees. Does not appear to be as common as the other commoner cuckoos, but widespread. The only one with yellow-brown on the abdomen. Lengths: female 17-18.5mm, male 15-16mm

 

Bombus rupestris (Fabricius 1793)
Cuckoo on the very similar B. lapidarius. Appears to be extremely rare in this county, but this may be partly because of this similarity and confusion. Lengths: female 18-23mm, male 14-17mm


Bombus sylvestris (Lepeletier 1832)
Cuckoo on B. pratorum and, perhaps, B. jonellus. I suspect that this bumblebee may be commoner than it appears to be, as it is so comparatively undistinguished in appearance. Females have an under-curved tip to the abdomen which, once seen, is a readily-remembered characteristic. Lengths: female 14-16mm, male 13-15mm


Bombus vestalis (Geoffroy 1785)
Cuckoo on B. terrestris, itself common. The commonest of the various cuckoos and seen in gardens as well as the wider countryside. The frequently-mentioned side patches of yellow between the white tail and the black band on the abdomen often become distinct bands of colour, which can be worrying. Lengths: female 20-22mm, male 15-17mm




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