Merodon equestris

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Cladus: Protostomia
Cladus: Ecdysozoa
Cladus: Panarthropoda
Phylum: Arthropoda
Subphylum: Hexapoda
Classis: Insecta
Cladus: Dicondylia
Subclassis: Pterygota
Cladus: Metapterygota
Infraclassis: Neoptera
Cladus: Eumetabola
Cladus: Endopterygota
Superordo: Panorpida
Cladus: Antliophora
Ordo: Diptera
Subordo: Brachycera
Infraordo: Muscomorpha
Sectio: Aschiza
Superfamilia: Syrphoidea

Familia: Syrphidae
Subfamilia: Eristalinae
Tribus: Eumerini
Genus: Merodon
Species: Merodon equestris

Merodon equestris (Narcissus bulb fly, greater bulb fly, large bulb fly, large Narcissus fly)[1] is a Holarctic species of hoverfly (Family Syrphidae).[2][3][4] [5][6][7] Like many other hoverflies it displays a colouration pattern similar to a stinging insect (a bumblebee in this case) as an evolutionary defense mechanism. Other syrphid bee mimics are Mallota, Arctophila, Criorhina, Pocota and Brachypalpus. Merodon species are distinguished from these by the very strong hind femora, which bear a large triangular projection on the underside near the tip. It flies in low vegetation while the other bumblebee mimics prefer higher vegetation layers.

Description

A stout fly with a small head. The tergites are black, without the dust spots or blue-purple sheen of other Merodon species. The thorax and abdomen are hidden by dense, long, erect hairs of variable colouration. Tibia 3 of the male has 2 spurs at the apex.[8] The larva is described and figured by Hodson (1932) [9] and it is illustrated in colour by Rotheray (1993).[10]
Distribution

In the Palearctic it is found from Fennoscandia south to Iberia and the Mediterranean basin, and Ireland east through Europe into Russia and Japan. In the Nearctic it is found from British Columbia south to California. It has been introduced to New Zealand.
Biology

Habitat: Open areas in deciduous forest up into the subalpine zone but significantly synanthropic, occurring in suburban parks and gardens and on horticultural land.[11] The adult flies low in April to July with a fast zig-zag flight, among ground vegetation frequently settling on bare ground. Adult M. equestris feed on pollen and nectar. They visit a large variety of flowers for nectar,[12] while the larvae feed internally in tissues of bulbs of Amaryllidaceae, and they are regarded as a horticultural pest, especially of Narcissus. A bibliography of the literature on the biology of M.equestris is given by Barkemeyer (1994)[13]
Colour forms

var. equestris (female)

var. equestris (female)
var. narcissi (male)

var. narcissi (male)
var. validus (female)

var. validus (female)

References

"Hoverflies". Retrieved 2009-12-12.
Stubbs, Alan E. & Falk, Steven J. (1983). British Hoverflies: An Illustrated Identification Guide. British Entomological & Natural History Society. pp. 253, xvpp.
Van Veen, M. (2004) Hoverflies of Northwest Europe: identification keys to the Syrphidae. 256pp. KNNV Publishing, Utrecht.addendum
Van der Goot,V.S. (1981) De zweefvliegen van Noordwest - Europa en Europees Rusland, in het bijzonder van de Benelux. KNNV, Uitgave no.32: 275pp. Amsterdam.
Bei-Bienko, G.Y. & Steyskal, G.C. (1988) Keys to the Insects of the European Part of the USSR, Volume V: Diptera and Siphonaptera, Part I. Amerind Publishing Co., New Delhi. ISBN 81-205-0080-6.
Coe, R.L. (1953) Diptera: Syrphidae. Handbks.ident.Br.insects, 10(1): 1-98. R.ent.Soc.London. pdf
Peck, L.V. (1988) Syrphidae. In: Soos, A. & Papp, L. (eds.) Catalogue of Palaearctic Diptera, 8: 11-230. Akad.Kiado, Budapest.
Bradescu, V. (1991) Les Syrphides de Roumanie (Diptera, Syrphidae), Clés de détermination et répartition. Trav.Mus.Hist. nat. Grigore Antipa, 31: 7-83.
Hodson, W.E.H. (1932) The large narcissus fly, Merodon equestris, Fab. (Syrphidae). Bull.Ent.Res., 23: 429-448
Rotheray G., 1993 Colour Guide to Hoverfly Larvae Diptera, Syrphidae in Britain and Europe Dipterists Forum pdf
Speight, M.C.D. (2011). "Species accounts of European Syrphidae (Diptera)" (PDF). Syrph the Net, the Database of European Syrphidae. 65: 285pp.
de Buck, N. (1990) Bloembezoek en bestuivingsecologie van Zweefvliegen (Diptera, Syrphidae) in het bijzonder voor elgië. Doc.Trav. IRSNB, no.60, 1-167.
Barkemeyer, W. (1994) Untersuchung zum Vorkommen der Schwebfliegen in Niedersachsen und Bremen (Diptera: Syrphidae). Naturschutz und Landschaftspflege in Niedersachsen, 31: 1-514.