Melanostoma mellinum (Linnaeus 1758)

Melanostoma mellinum is a very common species of hoverfly found in many parts of Britain, Europe including the Mediterranean basin and North Africa, the East Palearctic, and North America.

A small species, their wingspan range recorded is between 4.7 and 7.0 mm. Very similar to Platycheirus and other Melanostoma species, but with close inspection of some finer details, it can be identified with certainty. Adult males closely resemble Platycheirus clypeatus, but lack the flattening or broadening of the front legs characteristic of most Platycheirus males. Females resemble female Melanostoma scalare, sharing similar triangular tergite markings, but have a shiny, black frons, which separates them from M. scalare and most Platycheirus species. Also, M. mellinum may prove to be a species complex.

Their preferred habitat include grasslands and moorlands, including those in hilly and mountainous regions. Adults can be found feeding on the pollen of grasses (Poaceae) and other wind-pollinated plants.

Little is known of their biology, but the larvae are suspected to be a general predator of small insects in leaf litter.

Flight times in Britain and Ireland are from April to October with peaks in late May - early June and from July to August.

Head: Colour brownish black. Angle of approximation of eyes 80°–90°. Eye contiguity about as long as frontal triangle. Ocellar triangle slightly longer than wide with dark pile and with thin grey dusting. Occiput very narrow and dorsally usually with dark pile and laterally with pale pile. Frontal triangle with indistinct or thin grey dusting. Lateral parts of frontal triangle with dark pile. Face shining with indistinct or thin grey dusting. Lateral parts of face with pile which colour varying from completely pale to almost completely dark. Gena about as wide as basoflagellomere and with greyish dusting. Antenna mainly dark brown, usually basoflagellomere with yellow spot basally at ventral side. Basoflagellomere about 1.4 times as long as its width. Arista usually yellowish brown and about twice as long as basoflagellomere. Longest pile of arista at most half width of arista at base as in Fig. 4B. Thorax: Scutum shining brownish black except for thin greyish dusting at anterior margin. Scutum with erect pile and with shorter semi-adpressed usually mainly pale pile on anterior margin. Pile rarely mainly dark on scutum. Anterior part of scutum almost always with short erect pile which length about fourth part of length of scutellum. Postpronotum totally covered by thin greyish dusting. Notopleuron usually covered by thin greyish dusting. Scutellum shining brownish black. Scutum and scutellum with pile which colour varying from totally pale brown to almost totally dark. Pleura brownish black and usually with thinly grey dusting. Pleura with pale or brownish erect pile. Calypter brownish with pale brownish pile at edge. Halter yellow with slightly darkened base of stem. Wing: Usually completely microtrichose, rarely with small bare area on base of cell BM. Membrane with indistinct brownish ting. Stigma usually yellowish brown. Legs: Coxa black with grey dusting. Trochanter dark brown. Femur usually mainly black except yellow apical part. Tibia usually mainly yellow with dark brown ring varying size. Metatibia usually with a longer dark ring than other tibiae. Tarsus dark brown except mesotarsus with the two basal segments yellow. Leg with pale and dark pile mixed. Abdomen: Terga dark brown or black with weak greyish dusting. Tergum 2 with pair of yellow oval maculae. Terga 3 and 4 with pair of yellow elongated maculae. Terga 1 and 2 laterally with long pale pile. Terga with varying amount of dark and pale semi-adpressed pile outside of yellow maculae. Only pale pile on yellow maculae. Terga 2, 3 and 4 each about as long as wide. Sterna with weak dusting and with pale semi-adpressed pile. Sternum 2 about 1.3 times as long as its width at its posterior margin. Sternum 3 about 1.2 times as long as its width at its anterior margin. Sternum 4 about as long as its width at its anterior margin. Shape of sterna 2–4 are shown in Fig. 5D. Male genitalia: Cercus and surstylus (Fig. 6D). Postgonite short and without distinct ridges laterally (Figs 7D, 8D). Postgonite ventrally in Fig. 9D. The hypandrial margin at postgonites with long triangular projections, index DL less than 1.2 (Figs 10D, 11D). Similar to male, but differs as follows: Head: Frons shining except greyish dusted triangles. Ventral to the dusted triangles the thinly dusted area is not connected to the sides of lunule. Frons at level of front ocellus slightly narrower than length of antenna. Dorsal part of frons with dark pile and ventral part of frons with pale pile. Occiput as broad as two diameters of an ocellus and usually dorsally with pale and dark pile and laterally with pale pile. Thorax: Scutum and scutellum with short pale pile. Calypter whitish yellow with whitish pile at edge. Legs: Coloration of femur varies from mainly yellow to mainly dark. Metaleg usually largely darker than other leg. Abdomen: Some specimens have all terga dorsally only with pale yellowish semi-adpressed pile. Tergum 2 without or with pair of small yellow oval maculae. Terga 3 and 4 with pair of yellow elongated triangular maculae of varying size or yellow maculae lacking. Tergum 5 at anterior margin without or with pair of short yellow maculae. Tergum 2 about 0.5 times as long as its width at its posterior margin. Tergum 3 about 0.5 times as long as its width at its posterior margin. Tergum 4 about 0.6 times as long as its width at its posterior margin. Sternum 2 about 0.6 times as long as its width at its posterior margin. Sternum 3 about 0.6 times as long as its width at its anterior margin. Sternum 4 about 0.6 times as long as its width at its anterior margin. Sterna 3 and 4 with posterior margin of sternum distinctly broader than width of anterior margin of sternum. Sternum 4 is at most slightly longer than sternum 3. Shape of sterna 2–4 are shown in Fig. 12E, F.

A very common and abundant species, known from the whole Palaearctic area and North Africa.