The colour forms of Volucella bombylans
V. bombylans V. bombylans
Volucella bombylans vars. plumata (L) and bombylans (R). Pictures © Malcolm Storey BioImages.
Volucella hoverflies are commensals in the nests of social bees and wasps. The larvae can be found, sometimes in large numbers, in the nests after the host colony has finished. Only two species are known from the north of Scotland, V. bombylans, considered here, and the very distinctive V. pellucens - a large stout fly with the abdomen white in front and black behind. The latter is common on Bramble Rubus fruticosus and other flowers.

V. bombylans forms

The colour forms of Volucella bombylans recorded in the Highlands and Islands. L to R: plumata, the commonest form; haemorrhoidalis, infrequent; bombylans, rare; and the black and white form, also rare.

Distribution and habitat

The distribution (records from my database only) of the four forms is shown in the maps. All are found predominantly in moorland, heath or forest edge, and Erica cinerea is an important nectar source. The numbers give an idea of the difference in abundance of the forms. Adults are active during July and August.
Map plumata Map haemorrhoidalis Map black forms
Volucella bombylans var. plumata Volucella bombylans var. haemorrhoidalis

Maps created with DMAP.

 Volucella bombylans var. bombylans (red dot), and black form with white tail (black dots).
47 squares, 55 records, 87 individuals 10 squares, 10 records, 13 individuals

1 square, 1 records, 1 individuals (bombylans)

2 squares, 2 records, 2 individuals (white-tailed)

Mimicry

The plumata form of this species is an extremely good bumblebee mimic. It is the size and shape of a worker Bombus lucorum or B. hortorum, and its behaviour resembles a foraging bumblebee. Both these potential models are common in the Highlands and Islands and lucorum especially shares its habitat. The other forms are much less convincing. The nearest potential model for haemorrhoidalis is B. pratorum, but the resemblance in the field is poor and the habitat is not generally shared. B. lapidarius, a potential model for bombylans, does not occur in most of the area. The black and white form has no bumblebee match.

Records

Any records of the three less common forms can be reported initially by email giving date, place, six-figure grid reference and any other relevant details. Directions for sending specimens (which will be useful for confirmation) will then be provided.
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