Erotides cosnardi

Erotides cosnardi - Cosnard's Net-winged

A rare saproxylic beetle, found only in the Wye Gorge/Forest of Dean area and the South Downs.

  • Rarity: 3 sites in England and Wales

  • Causes of decline: Loss of large old beech trees and poor management of remaining ancient woodlands.

Before the Species Recovery Trust started working on Cosnard’s Net-winged Beetle in 2014, it had been recorded less than 10 times in total in the UK and we knew almost nothing about its ecology or life history. We have been working with partner organisations over the last few years to improve our understanding of this beetle and what it needs to survive, but there is still a long way to go

What we do know is that the species is found in the Wye Valley and the South Downs and relies on dead and dying wood in ancient forests for survival. It also appears to be attracted to recently cut tree stumps, which may play a role in mating behaviour. To protect this species, we need to build on this knowledge and gain a better understanding of larval ecology in particular, so that we can protect it at every stage of its life cycle.

Cosnard's Net-winged Beetle Surveys and site assessment in the Wye Gorge 2018

This document reports on survey work during the 2018 flight period for Cosnard’s net-winged beetle Erotides cosnardi in the Wye Gorge, following up on work carried out during 2017: 

  • Field trials of using freshly cut tree stumps to attract male beetles, as per observations made at a goat willow stump on the edge of Highbury Wood NNR, Gloucestershire, in 2017, all proved negative; no cosnardi were found on freshly cut tree stumps;


  • Male beetles were however observed on an older but undecayed cut slice of a beech trunk at Little Doward, Herefordshire, but were apparently only present for one day, suggesting a sub-optimal situation for aggregation;​

  • A male beetle was taken by one of a series of flight interception traps being operated by Natural Resources Wales in woodlands at the Chepstow end of the wooded gorge; this is the first time that the species has been found at this other end of the Wye Gorge;​

  • Continued exploration of the woodlands in the upper gorge has provided insights into the habitat availability at the local landscape scale, with Little Doward and the adjoining Seven Sisters Rocks area as the outstanding area for old growth woodland conditions, but with potential breeding trees scattered more thinly throughout the system.