Eumerus strigatus, the onion bulb fly, is a fairly common species of syrphid fly observed across Europe. Also found in north-central North America and other scattered locations as an introduced species from infested bulbs. Syrphid flies are also known as hover flies or flower flies because the adults are frequently found hovering around flowers from which they feed on nectar and pollen. The larvae feed on various bulbs.
Description External images For terms, see: Morphology of Diptera.
Wing length: . Stigma are yellowish or light brown. Femora 3 is simple. Tergites are blackish, absolutely without reddish-brown markings. Male ocelli are in an equilateral triangle. Male genitalia figured by Van Veen (2004).Van Veen, M. (2004) Hoverflies of Northwest Europe: identification keys to the Syrphidae. 256pp. KNNV Publishing, Utrecht.addendumVan 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. .Coe, R.L. (1953) Diptera: Syrphidae. Handbks.ident.Br.insects 10(1): 1-98. R. ent. Soc. London. pdf Bradescu, V. (1991) Les Syrphides de Roumanie (Diptera, Syrphidae), Clés de détermination et répartition. Trav.Mus.Hist. nat. Grigore Antipa, 31: 7-83. The larva is described and figured by Heiss (1938).Heiss, E.M. (1938) A classification of the larvae and puparia of the Syrphidae of Illinois exclusive of aquatic forms. Univ.Illinois Bull., 36: 1-142.
Distribution Palaearctic, Fennoscandia South to Iberia and the Mediterranean basin, Ireland east through Europe into Turkey and Russia. Also, from the Urals to the Pacific coast (Sakhalin) and Japan. Introduced to the Nearctic and Australia and New Zealand.Fauna EuropaeaPeck, L.V. (1988) Syrphidae. In: Soos, A. & Papp, L. (eds.) Catalogue of Palaearctic Diptera, 8: 11-230. Akad. Kiado, Budapest.
Biology The habitat is wetlands, deciduous woodland, open ground, seasonally-flooded grassland, and open, dry unimproved pasture, including dune grassland. Also in horticultural land and suburban gardens. In dry grassland often settles on the ground, on stones etc. Flowers visited include umbellifers, Allium ursinum, Convolvulus, Eschscholzia californica, Euphorbia, Fragaria, Leontodon, Papaver, Potentilla erecta, Ranunculus, Sonchus arvensis, Taraxacum. The flight period is May to September. A bulb feeder. It is a minor pest of Liliaceae, parsnip, carrot, potato, asparagus, artichoke roots (Cynara scolymus).de Buck, N. (1990). "Bloembezoek en bestuivingsecologie van Zweefvliegen (Diptera, Syrphidae) in het bijzonder voor België". Doc.Trav. IRSNB, no. 60, pp 1-167.
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