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Parasyrphus nigritarsis (Zetterstedt, 1843)

Identification

Identification difficulty = 4. microscope_icon camera_icon_question according to Ball & Morris, 20241

Synonymy

Syrphus nigritarsis Zetterstedt in Coe(1953)2.

Biology

The larva is predaceous upon the larvae of Chrysomelid beetles on Alder Alnus glutinosa (Chrysomela aenea) sallows Salix sp. (Lochmaea capraea) and Dock Rumex (Gastrophysa viridula). These generally occur in the vicinity of sallows and Alder along sandy banks of rivers and streams. Adults visit umbellifer flowers and may also be found sun-basking on leaves.

Flight period

The following plots show the number of unique records per week that were not reported to be of eggs, larvae or pupae. phenology

Status

Lower Risk (Nationally scarce) - Ball & Morris, 20143. Endangered (RDB1) - Falk, 19914 and Shirt, 19875.

Distribution

This is mainly a northern and western species that is widely distributed across Scotland, Cumbria and Wales, but is also reported from East Anglia, South Hampshire and Cornwall. Since its larval requirements have been better understood, it has been recorded much more frequently and is now known to be more widespread and frequent than was previously thought. dotmap

Trends

The following plots show the Frescalo TFactor vs year and a map of the rescaled frequency (all records) for the species. For an explanation see here. trend

  1. Ball, S., & Morris, R. (2024). Hoverflies of Britain and Ireland. WILDGuides (3rd ed.). Oxford: Princeton University Press. ↩

  2. Coe, R. (1953). Diptera: Syrphidae. Handbooks for the Identification of British Insects, 10(1), 1–98. ↩

  3. Ball, S., & Morris, R. (2014). A review of the scarce and threatened flies of Great Britain. Part 6: Syrphidae. ( No. 9). Species status (pp. 1–130). Peterborough: JNCC. ↩

  4. Falk, S. (1991). A review of the scarce and threatened flies of Great Britain. ( No. 39). Research and Survey in Nature Conservation (pp. 1–194). Peterborough: NCC. ↩

  5. Shirt, D. (Ed.). (1987). Red Data Books: 2. Insects. Peterborough: NCC. ↩