Northern Ireland's Priority Species

Acronicta psi – grey dagger

Acronicta psi

Acronicta psi (Linnaeus, 1758)
Family: Noctuidae

The Grey Dagger is an attractive, fairly common, medium-sized, grey Noctuid. It is on the wing throughout much of the summer. It occurs in a wide variety of habitats and feeds on many different trees and shrubs. It has declined in the UK by 65% over a 25 year period in the UK but in Northern Ireland there is no evidence of such a decline.

In brief

  • Widespread and relatively common throughout Northern Ireland
  • The adult flies from May to August
  • Most likely to be encountered at light
  • A Northern Ireland Priority Species because of declines detected in other parts of the UK where it has undergone a 65% decline over a 25 year period

Species description
The forewing is pale to dark grey with a series of well-defined black lines arranged along the length of the wing. The boldest is the line from the wing base. Most of these lines have short branches which create the dagger shaped marks after which the moth is named.

Life cycle
The adult flies from mid-May to August. It overwinters as a pupa in a cocoon placed under the bark of a rotten tree or branch. The distinctive, brightly coloured caterpillar can be seen from late July into October. This species will eat a wide variety of trees and shrubs including Hawthorn, Blackthorn, Lime, Elm and Mountain Ash. As a consequence it occurs in a wide range of habitats.

Similar species
Confusion is only likely with Dark Dagger which has yet to be definitively recorded in Ireland although because it can only be separated by genitalia examination it may well be present.

How to see this species
This species is readily attracted to light and trapping of woodlands or larger gardens is likely to be productive.

Current status
Widespread and relatively common throughout Northern Ireland.

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 (65% 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.

Proposed objectives/actions

  • Occurs on a number of designated sites
  • 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

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