Adapted from Vockeroth (1969).
Large robust species with broadly oval, moderately convex abdomen with broad, divided, yellow or greenish-yellow fasciae.
Megasyrphus species have pilose eye, the pile below less dense and rather restricted; face yellow with dark brown to black medial vitta; scutum black, shining, at most very slightly yellowish laterally; scutellum yellow-brown; pleura blackish, shining, the posterior part of anepisternum and dorsal part of katepisternum distinctly pale poIlinose, sometimes slightly yellowish in ground colour; dorsal and ventral katepisternal pile patches narrowly separated posteriorly because of posterior broadening of both patches, otherwise broadly separated; metasternum with many long black pile; metacoxa with tuft of strong pile at posteromedian apical angle; vein R4+5 shallowly, broadly, symmetrically, but distinctly dipped into cell R4+5; wing membrane entirely microtrichose; abdomen broadly oval, usually distinctly convex dorsally, with strong margin from distal third of tergum 2 to end of tergum 5.
Synonyms:
Scaeva annulipes Zetterstedt, 1838: 599.
Didea fulvipes Bigot, 1884: cxvi.
Musca erratica Linnaeus, 1758: 593.
New description:
MALE.
Head: Face with facial tubercle, yellow with medial broad dark vitta, yellow pilose laterally, black pilose medially and laterodorsally; gena brown, pale pilose; frontal triangle black, black pilose; holoptic, eye densely pilose; vertical triangle black, black pilose; antenna and arista black; occiput black, silver pollinose, yellow pilose.
Thorax: Scutum subshiny black, yellow pilose; postpronotum dark, bare; scutellum yellow, black pilose except yellow pilose anteriorly, subscutellar fringe complete, sparse with black pile. Pleuron black, with long yellow pile; metasternum pilose; calypter yellow; plumula white; halter brwon; spiracular fringes yellow. Wing: Wing membrane hyaline, entirely microtrichose. Alula broad, microtrichose. Legs: pro- and mesoleg dark brown except femora yellow on apical hal and tibiae yellow; metaleg dark brown except metafemur yellow on apical 1/5-1/6 and metatibia yellow on basal half.
Abdomen: oval, terga 2-5 margined. Terga yellow pilose anteriorly, black pilose posteriorly; tergum 1 black; tergum 2 black with two medial broad yellow maculae; terga 3 and 4 black with subbasal broad yellow fascia with posterior margin strongly emarginated; tergum 5 black; sterna yellow with subapical broad black fascia medially pointed anteriorly.
FEMALE.
Similar to male but much larger, frons shiny black with two lateral white pollinose maculae; posterior anepisternum and dorsal aprt of katepisternum densely white pollinose; basitarsomeres basally yellow; metatibia yellow with medial black ring; tergum 4 with yellow fascia on posterior margin; tergum 5 yellow with broad black inverted V-shaped fascia.
Megasyrphus erraticus (Linnaeus, 1758).
Linnaeus, C. (1758) Systema naturae... Ed. 10, Vol. 1. 824 pp. L. Salvii, Holmiae [= Stockholm].
GenBank accession number for this species are: protein-coding COI gene (EF127357), rRNA 28S gene (EF127438) and 18S gene (EU431545).
While it is apparent that Didea, Eriozona and Megasyrphus are closely related there is less agreement on whether the species consigned to these genera should all be grouped under Didea or segregated under the three existing genera (see, for example, Vockeroth and Thompson, 1987; Rotheray and Gilbert, 1989; Vockeroth, 1992). However, recognition of Megasyrphus as a separate genus carries with it the implication that Eriozona should also be regarded as a separate genus, and vice versa, to judge from the information now available (Speight 2010).
Rotheray and Gilbert (1989) recovered Eriozona as sister group of Eupeodes and Scaeva, while Didea and Megasyrphus were resolved together in the same polytomy. A similar placement resulted from the study by Rotheray and Gilbert (1999), when Didea and Megasyrphus were resolved together, and Eriozona as sister group of Dasysyrphus, Paragus, Eupeodes, Scaeva and Ischiodon.
Mengual et al. (2008) recovered Eriozona syrphoides as sister group of Dideoides coquilletti, being Dideopsis aegrota the sister group of both. As a sister group of this clade their results paced Megasyrphus and Didea.
Flowers visited by aduts: yellow composites; white umbellifers; Bellis, Calluna vulgaris, Cardamine pratense, Cirsium vulgare, Crataegus, Epilobium angustifolium, Euphorbia hyberna, Geranium, Lonicera periclymenum, Prunus spinosa, Ranunculus, Rubus idaeus, R. fruticosus agg. Salix, Sorbus aucuparia, Stellaria, Veronica, Viburnum (Speight 2010).
Flight period for European specimens: May/July, with occasional specimens on through August into September, particularly at more northertly latitudes (Speight 2010).
Very wide-spread species that ranges from Fennoscandia south to the Pyrenees (becomes increasingly montane toward southern parts of its range); from Ireland eastwards through central Europe and the Alps (plus Apennines in Italy; northern parts of the former Yugoslavia) into European Russia and on through Siberia to the Pacific coast (Sakhalin and Kunashir islands); the Himalayas (Nepal, see Claussen and Weipert, 2003); and in North America from Alaska to Mexico (Speight 2010).
Adults inhabit clearings and tracksides etc. from the altitude of Fagus/Picea forest upwards into the conifer forest zone; males hover at 3 - 5 m. in dappled sunlight beneath the canopy in conifer forest; females are apparently primarily arboreal, descending to visit flowers (Speight 2010).
Adults' preferred environment: conifer forest (Abies, Picea, humid Pinus) and plantations (Speight 2010).
Larva was described and figured by Dusek & Laska (1967, in German) and Goeldlin (1974, in French); recorded by Kula (1982) as overwintering among leaf litter on the floor of spruce (Picea) forest.
unless otherwise stated