|scientific name Syrphus torvus |
Boreal regions, mixed forest, parks, gardens.
Adult flight period is quite extensive, occurring from April to November.
Approximately 7 to 15 mm in length, black and yellow body, face yellow. Although S. torvus looks superficially very much like both S. ribesii and S. vitripennis (refer to descriptions for these two species), its distinctive characteristic is that both males and females have hairy eyes. The hairs on the male eyes are denser and longer than those on the female eyes, however this characteristic is quite clear for both sexes (under a microscope). As well, the yellow bands of tergites 3 and 4 are complete, and both sexes have a hind femur that is black for approximately the basal three-quarters (Vockeroth 1992).
Probably multivoltine, with the larva as the overwintering stage. Syrphus torvus is aphidophagous and polyphagous, seeming to prefer shrubs and trees to herbs (Schneider 1969). Sendstad (1976) reported that they seem to prefer the vegetation-rich slopes beneath bird cliffs in Spitsbergen, Svalbard.
Widespread, not of concern.
Syrphus torvus is entirely aphidophagous, and the larvae have been recorded on the aphids Cinara carolina, and on Euceraphus spp. (Vockeroth 1992). Adults feed on pollen and nectar.
Syrphus torvus is widespread throughout Canada, and from Alaska down to California and Mississippi. It is also found in much of Europe (including as far north as Svalbard), as well as Asia, with records from Siberia and Nepal (Vockeroth 1992).
For a clear description of an effective and simple method for rearing S. torvus see Frazer (1972).
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