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The grey dagger (Acronicta psi) is a moth of the family Noctuidae. It is found from Europe and North Africa to northern Iran, central Asia, southern and central Siberia and Mongolia. In the Levant it is found in Lebanon and Israel.

Grey dagger
Acronicta psi.jpg
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Noctuidae
Genus: Acronicta
Species: A. psi
Binomial name
Acronicta psi
(Linnaeus, 1758)
  • Triaena psi
Grey dagger larva feeding on a Japanese cherry tree in early autumn

This species has grey forewings with bold black dagger-shaped markings. (The Latin specific name also refers to these markings, as resembling the Greek letter psi ψ.) The hindwings are dirty grey, generally paler in the male. The wingspan is 34–45 mm. This moth is very similar to the dark dagger (Acronicta tridens) and identification is generally only possible by minute examination of the genitalia. However, in general this moth is generally darker in colour than the dark dagger and always lacks the white hindwings often present in the male of that species. The grey dagger flies at night from June to August [1] and is attracted to light and sometimes to sugar.

The larvae of the two species are very different (see below).

The larva is whitish below and black above with red spots and a bold yellow stripe along the back. It has a distinctive horn just behind the head (absent from the larva of dark dagger). It feeds on a wide range of plants, mainly trees and shrubs (see list below). The species overwinters as a pupa.

  1. ^ The flight season refers to the British Isles. This may vary in other parts of the range.

Recorded food plantsEdit


  • Chinery, Michael Collins Guide to the Insects of Britain and Western Europe 1986 (Reprinted 1991)
  • Skinner, Bernard Colour Identification Guide to Moths of the British Isles 1984

External linksEdit