A Quick Guide to- the Bee Fly

Originally published 18 May 2015.

The large bee fly, Bombylius major, is fairly common in southern Britain, yet many people are unaware of this insect. They are on the wing from late March until late May and during this time, social media sites often get many posts containing pictures of the insect, often captioned with ‘what is this?’ or ‘what type of bee is this?’.

As the name suggests, the bee fly is a member of the fly family, from the order Diptera. However, as a very convincing bee mimic- having a yellow and black striped, hairy body- the fly is often mistaken for a bumblebee. The main feature that sets the fly apart from a bee is the long, straight proboscis it has and the fact that the fly has only one set of functional wings, whereas bumblebee’s have two sets of wings. The large bee fly, B.major, is the most common species of bee fly in the UK and can be told apart from other bee fly species by the strong dark mark across the front half of its wings. It is also the largest species in the UK. Despite these identification features, it is difficult to differentiate between bee fly species, of which there are several in the UK.

Bee flies are excellent fliers and can whirr their wings to warm their flight muscles when temperatures are low. Once in flight, they can keep their temperature up by either flying high to absorb direct heat from the sun, or by flying low to absorb ground heat. When cold ,they will perch vertically, pointing upwards until the temperature rises. They can remain perched this way for up to a week. Bee flies feed on nectar, using their proboscis to do so. They hover close to plants and rest two legs of the flower when feeding.

The large bee fly, along with other species in the genus Bombylius, are parasitic and lay their eggs in the nests of their hosts- solitary mining bees and bumblebees. They do this by hovering over nests or burrows and dropping or flicking their eggs into the nest. Before they deposit their eggs, they coat them in soil or dust. This adds weight to the eggs and may also be a form of camouflage. Once the larvae hatch, they will crawl further into the nest/burrow and feed on mature bee larvae, eventually killing them. Therefore, the abundance of the bee fly depends upon the abundance, and conservation, of its host species.


Bee-flies | Soldierflies and Allies Recording Scheme. 2015. Bee-flies | Soldierflies and Allies Recording Scheme. [ONLINE] Available at: http://www.brc.ac.uk/soldierflies-and-allies/bee-flies. [Accessed 18 May 2015].

Behaviour | Natural History Museum. 2015. Behaviour | Natural History Museum. [ONLINE] Available at: http://www.nhm.ac.uk/nature-online/species-of-the-day/biodiversity/loss-of-habitat/bombylius-major/behaviour/index.html. [Accessed 18 May 2015].

Bee-fly – Entomologists’ glossary – Amateur Entomologists’ Society (AES). 2015. Bee-fly – Entomologists’ glossary – Amateur Entomologists’ Society (AES). [ONLINE] Available at: http://www.amentsoc.org/insects/glossary/terms/bee-fly. [Accessed 18 May 2015].

Bee-flies and false widow spiders confound public | Natural History Museum. 2015. Bee-flies and false widow spiders confound public | Natural History Museum. [ONLINE] Available at: http://www.nhm.ac.uk/about-us/news/2014/apr/bee-flies-and-false-widow-spiders-confound-public129835.html. [Accessed 18 May 2015].

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Rachel Davies

Rachel Davies

Currently studying for an MRes in Wildlife Conservation at the University of Chester. Research focuses on the White-faced Darter, an endangered dragonfly species here in Britain. Rachel also has a blog titled 'working with wildlife'.
Rachel Davies

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