Red-eyed Damselfly (Erythromma najas) is a scarce and localised damselfly in Monmouthshire, found at a restricted set of sites in the south and east of the county. Prior to 2017 it was the only Erythromma damselfly in the county but since then, its relative, Small Red-eyed Damselfly (E. viridulum) has colonised and is now the more common of the two species.

The oldest record we have in our dataset is from Coity Tips, Blaenavon on 11 August 2007 (observer Steve Williams), although the species has not been seen here since.

Current distribution in the county: what we know

Post-2019 records come mainly from sites in the south of the county close to Newport and Cwmbran: Marshfield on the Gwent Levels, Cleppa Park ponds, Tredegar House lake and Cwm Hedd to the west of Newport, Ynys y Fro reservoirs, Llantarnam ponds, the Monmouthshire and Brecon Canal at Sebastopol, several ponds and lakes on the Celtic Manor golf courses, Spytty and Lliserry ponds in eastern Newport, and Uskmouth nature reserve.

Elsewhere, the species has been found recently at only three sites: Magor Marsh, the River Wye at Bigsweir Bridge and a fishing lake near Trellech Grange.

Current distribution in the county: what we don’t know

Prior to 2020, in addition to the Coity Tips record, Red-eyed Damselfly was recorded from the following additional sites, all in the south of the county, and it would be valuable to know if it is still present at any of these (year of most recent record in brackets): Mathern fishing ponds (2017), Goldcliff lagoons (2014), Rogiet country park (2013) and Dewstow garden in Caldicot (2011). It is possible that some of these records relate to Small Red-eyed Damselfly, which may not have been ‘on the radar’ of the observers at the time.

There is a 2018 record from the River Wye at Monmouth, and searches here and at other sites along the Wye will help in establishing the extent of its distribution on the river, and to assess the effect that ongoing severe agricultural pollution is having there. Although there are no records from the Usk it is possible that the species occurs there too. It was recorded in 2016 on the Cwmbran stretch of the Monmouthshire and Brecon canal; searches here and along other sections of the canal would be useful to confirm the full extent of its population on that waterbody.

Distribution elsewhere

Red-eyed Damselfly is uncommon in Wales, where we are on the western edge of its British distribution: it mainly occurs in southern counties west to Carmarthenshire, with another population on the Severn from Newtown to the English border, and a few sites in far northeastern parts of the country. It is widespread in England as far north as Yorkshire, but is absent from Scotland. Elsewhere in Europe, it is found from France east to Russia, north to Scandinavia and Finland, and south to northern Italy and the Balkans; it is also found throughout Asia east to Japan.