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.

In 2018, we organised for a number of freshly cut beech stumps to be created in the Wye Gorge, in the hope that they would attract Cosnard's Net-winged Beetle (which we had previously found congregating on freshly cut stumps). We then undertook survey work over the flight period to see if any of the stumps were being used by the beetles. 

No beetles were found using the stumps, but male beetles were observed on an older but undecayed cut slice of a beech trunk at Little Doward, Herefordshire. This provides further evidence that these stumps do seem to be used by the beetles, potentially in their mating behaviour. However, further investigation is needed to confirm this.