Gymnocheta viridis

If you're looking to develop an interest in a different branch of natural history, then an interest in Diptera may be the answer.

As is presently the case with several other insect orders, Diptera study and identification is a much neglected aspect of Nottinghamshire entomology and there are very few people actively recording flies in the county.

Flies are a difficult lot to get to grips with and many who do go on to develop an interest in them, often begin with Hoverflies (Syrphidae) before eventually looking at some of the more difficult and less studied families.

In recent years, and to a large degree through interest generated through a wide range of internet chat groups, several Diptera families have seen an increase in interest.

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The majority of species still remain impossible to identify from the average photograph, but some identifications can be confirmed through good quality images, showing the relevant identifcation features from a number of angles and in good light. However, an on-line identification still usually requires the willingness and knowledge of experts.

Gymnocheta viridis in Nottinghamshire

Tachinid Flies (Tachinidae) are parasitoids of other insects (generally Lepidoptera) and are one family to have benefited from an increase in interest and over the past few years. As this recent interest has also become apparent in Nottinghamshire, the number of records we have been sent for the distribution maps, has subsequently also increased. In particular, the number of records of the metallic green Tachinid Gymnocheta viridis (Fallén, 1810), has greatly increased over the past few years.

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Gymnocheta viridis is a readily identifiable Tachinid, often allowing a close enough approach to get decent photographs of and the long bristles on the abdomen are distinctive enough. When seen well, the only real confusion species is Chrysosomopsis aurata (Fallén, 1820).

Although one of the more distinctive Tachinids, to those new to Diptera, Gymnocheta viridis does also tend to resemble a long-legged 'Greenbottle' (Lucilia sp) so familiar to many. However, a decent photograph should quickly determine G. viridis from any Lucilia sp.

Nottinghamshire distribution

It is an early species to appear and the males are often recorded on sheltered, sunny tree trunks in a wide range of habitats from late March through to June.

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Although it is primarily a fly of well wooded areas, we have recorded it from a variety of sites ranging from Debdale Lane and a supermarket car park in Mansfield Woodhouse, to the banks of the River Trent at Besthorpe NR near Newark. In Nottinghamshire, the majority of records are presently from the north-western quarter of the county, although much of this is undoubtedly due to recorder bias and we believe G. viridis to be more widespread than the map indicates.