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Greater Bee Fly

Bombylius major

Summary 6

The Large Bee-fly, Bombylius major, is a bee mimic. The eggs are flicked by the adult female toward the entrance of the underground nests of solitary bees and wasps. After hatching, the larvae find their way into the nests to feed on the grubs.

Behaviour 7

The adult bee-flies feed on nectar and sometimes pollen. They often hover next to the plant and rest two legs (front or hind) on the flower whilst feeding.They are incredibly fast and agile fliers. They tend to fly at 0.5 metres above ground, but can reach up to 3 metres.Many individuals fly along the ground to absorb heat, whilst others fly further up trees to maximise direct sunlight. When cold, the bee-flies perch vertically, pointing upwards, and they can remain in this position for a week or even longer (Knight 1967).Adults will also whirr their wings to warm up the flight muscles before take off.

Biology 8

The adult has:

  • a long proboscis
  • a dark chocolate/brown front margin to the wings that’s 6–12.5mm in length
  • wings 9–14mm in length
  • long legs

Females will flick eggs into the tunnels of solitary bees or in a habitat that is suitable for the host species. There are several host species, particularly digging bees such as Andrena sp. (Boesi et al, 2009, Paxton and Pohl, 1999).Once in the tunnel, the egg hatches and the worm-like maggot crawls into an open host cell. It remains inactive until the host larva is about to pupate.The bee-fly larva then becomes a maggot-like ectoparasite and attaches to the outside of the host, sucking out the body fluids (Oldroyd, 1964, Stubbs and Drake 2001). This is called hypermetamorphosis - the different larval instars are present in 2 or more different forms.The pupal stage is variable, but some will overwinter, with records in Britain and Sweden recording a quiescent stage that may last for two years (Stubbs and Drake 2001, Paxton and Pohl, 1999).Members of the genus Bombylius fly early in the year and are found from April to June in Europe, North America and some parts of Asia.Temperature determines the distribution and emergence of B. major and it will not fly in temperatures less than 17ºC. The adults exhibit courtship rituals - males hover at height and exhibit territorial behaviour which includes darting at rival males and spinning at females.

Distribution ecology 9

Bombylius major has been found in many countries across all biogeographical regions apart from Australasia.It is the most common bee-fly species in the UK where it occurs in southern England, the Midlands and the Welsh lowlands, but has also been recorded in southern Scotland and along the north west coast.UK distribution of Bombylius major on the National Biodiversity Network website

Habitat
Bombylius major is found in a wide variety of habitats including gardens and the edges of woodlands. Its major requirement is the presence of the host species. Loss of host habitats therefore has a direct impact on the survival of this species.

General description 10

16-22 mm long, 40-50 mm wingspan. Anterior half of wings dark brown and opaque, posterior half transparent. Hair exceptionally dense with orange tint. Characteristics shared with other Bombylius species include a slender first antennal segment, long scattered bristly hairs, holoptic males, conspicuously bristled hind femora, and a distinct intercalary vein (Hull 1973).

Introduction 11

The large bee fly is a bee mimic - it resembles a small bumble bee.The adult flies are striking and have a hairy body with long hairy legs and a characteristically long, slender tongue which they use for nectar retrieval whilst hovering beside a flower head.Bombylius major larvae parasitize beetle larvae as well as the brood of solitary wasps and bees - another reason for its name.The female has been seen to flick her eggs mid-air into the ground bees’ and wasps’ nests.

Sources and Credits

  1. (c) Anders Illum, some rights reserved (CC BY-NC-ND), http://www.flickr.com/photos/27631936@N05/3441349467
  2. (c) S. Rae, some rights reserved (CC BY), https://www.flickr.com/photos/35142635@N05/16614695959/
  3. (c) oldbilluk, some rights reserved (CC BY-NC-SA), https://www.flickr.com/photos/oldbilluk/7010666081/
  4. (c) Didier, some rights reserved (CC BY-SA), https://www.flickr.com/photos/didier57/3439288944/
  5. (c) Sarah Barker, some rights reserved (CC BY-NC-ND), https://www.flickr.com/photos/sarahgb/7631776952/
  6. Adapted by Allie Hay from a work by (c) Wikipedia, some rights reserved (CC BY-SA), http://en.wikipedia.org/wiki/Bombylius_major
  7. (c) Natural History Museum, London, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/12495914
  8. (c) Natural History Museum, London, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/12495915
  9. (c) Natural History Museum, London, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/12495916
  10. (c) University of Alberta Museums, some rights reserved (CC BY-NC), http://eol.org/data_objects/31888248
  11. (c) Natural History Museum, London, some rights reserved (CC BY-NC-SA), http://eol.org/data_objects/12486889

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