Northern Ireland's Priority Species

Xanthorhoe decoloraria – red carpet

Xanthorhoe decoloraria

Xanthorhoe decoloraria (Hubner, 1800-09)
Family: Geometridae

A very small, rare, pale-greyish butterfly-like moth with a distinctive dark central band. It has been recorded in July and early August mainly in upland areas. A Northern Ireland Priority Species because of major declines detected elsewhere in the UK. At present such data does not exist for Northern Ireland.

In brief

  • This is an extremely rare moth of mostly upland areas
  • Has a single generation on the wing in Britain from late June to mid August
  • Flies at dusk and is attracted to light
  • A Northern Ireland Priority Species because of declines detected in other parts of the UK where it has undergone a 69% decline over a 25 year period. There is some evidence that the species has exhibited a decline in Northern Ireland and as we are part of the UK it has been included on the Priority List

Species description
A member of the Geometridae it can be described as a member of this “butterfly-like” group of moths. It normally rests with the pale-greyish wings open revealing a reddish central band edged with blackish-brown. There are two small projections on the outer edge of the central band and there is feint diagonal mark at the tip of the comparatively broad and pointed forewings.

Life cycle
The caterpillar feeds on Lady’s-mantle from August to late May in Britain and over-winters as a small larvae. Lady’s-mantle has been found on all of the recently recorded sites in Northern Ireland. The moth pupates in a cocoon among the plant debris and is on the wing from late June to mid August.

Similar species
There are two similar species but the Flame Carpet has two projections on the outer edge of the central band and the Red Twin-spot Carpet normally has two dark spots at the outer edge of the forewing. The forewings of both these species lack the diagonal mark at the tip and are more rounded.

How to see this species
This little moth may be under-recorded due to the difficulties associated with trapping in upland habitats. Targeted recording in July in places such as Divis Mountain, Slievenacloy and at lower altitudes on Rathlin Island may prove worthwhile. The moth can be looked for by day as it is easily disturbed from its resting positions on stone walls, tree trunks and shaded rocks. It flies from dusk and comes to light.

Current status
Local and rare but widely distributed, it has only been recorded three times since 1990 in Counties Down and Antrim. The lack of recent records from some of its old sites in Armagh, Fermanagh, Tyrone and Londonderry suggests a decline on some sites and perhaps a lack of recording effort on others.

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 (69% 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. General management for Biodiversity will help maintain the species.

  • Occurs on an ASSI

Proposed objectives/actions

  • Increase Rothamstead Trap network to gather data on status
  • Encourage submission of records to the Moth recorder

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

Baynes, E.S.A. (1964). A revised catalogue of Irish macrolepidoptera (Butterflies and Moths). EW Classey, Hampton, Middlesex.
Porter, J. (1997). The colour identification guide to caterpillars of the British Isles. Viking, London.
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