Northern Ireland's Priority Species

Xestia castanea – neglected rustic

Xestia castanea

Xestia castanea (Esper, 1796)
Family: Noctuidae

This is a very scarce and localised species in Northern Ireland with an apparent westerly distribution. It is strongly associated with bog and heath habitats and flies late in the year from mid-August to mid-September. The commonest form has a clean reddish brown forewing with a distinct blackish dot in the upper half of the forewing. The hindwing is similar in colour to the forewing but duller. This species has declined in the UK by 70% over a 25 year period but in Northern Ireland it has always been thought of as rare and local.

In brief

  • Very scarce and local with no recent records from Counties Down or Londonderry
  • The adult flies in August-September
  • It is invariably encountered only at light
  • A Northern Ireland Priority Species because of declines detected in other parts of the UK where it has undergone a 70% decline over a 25 year period. There is no strong evidence that the species has exhibited a similar decline in Northern Ireland where it has always been considered very scarce or rare

Species description
A largish member of the Noctuidae, very typical of the family, with wings folded over the body. The base forewing colour is a rich reddish-brown, occasionally greyish, with a distinct small blackish dot in the upper half of the forewing and no other obvious features. The hindwing is a dull fuscous-brown with a distinct paler fringe.

Life cycle
Single brooded with adults on the wing mid-August to mid-September. Overwinters as a small caterpillar. Pupates underground during May. Feeds on a variety of heather species.

Similar species
Superficially similar to more obscurely marked Lesser Yellow Underwings but separated immediately by a view of the hindwing.

How to see this species
Light trapping or sugaring on the bogs and heaths of Fermanagh is the most likely route to success. Known to be in the Correl Glen area but likely to be in similar habitats elsewhere.

Current status
Very scarce and local with most recent records from Fermanagh, Tyrone and Armagh.

Why is this species a priority in Northern Ireland?

  • Listed as a UK Priority Species and therefore on the Northern Ireland Priority List by default
  • Rapid decline (70% over 25 years 1968-2002) assessed using Rothamstead trap data

Threats/Causes of decline
It is thought to be declining in the UK as a result of many factors, including habitat change, pollution and the use of pesticides.

Conservation of this species

Current action
In Northern Ireland there are no specific actions proposed for this species.

  • Occurs on a number of designated sites such as Corel Glen, County Fermanagh and Peatlands Park, County Armagh
  • Increase Rothamstead Trap network to gather data on status
  • Encourage submission of records to the Moth recorder

Proposed objectives/actions

  • None currently proposed

What you can do

  • Report all moth sightings to the Moth Recorder for Northern Ireland, Andrew Crory, or use the Butterfly Conservation Northern Ireland (BCNI) sightings web page at The BCNI database is managed by CEDaR and these records will then be used to update the Butterflies and Moths of Northern Ireland website.
  • Join Butterfly Conservation. Butterflies and Moths are in serious decline — with your support Butterfly Conservation can take action to reverse this.

Further information

The Butterflies and Moths of Northern Ireland

MothsIreland Website

The state of Britain's moths - an explanation as to how declines have been calculated

Background information on the Rothamstead Trap Surveys

UK Moths Website with an up-to-date distribution map

Skinner, B. (2009). 3rd revised and updated edition. The colour identification guide to the moths of the British Isles. Apollo Books.
Thompson, R. & Nelson, B. (2006). The Butterflies and Moths of Northern Ireland. NMNI, Belfast.
Waring, P. & Townsend, M. (2009). 2nd edition. Field Guide to the Moths of Great Britain and Ireland. British Wildlife.

Text written by:
Allen & Mellon