Grey dagger

This species can be found from Europe[1] and North Africa to northern Iran, central Asia, southern and central Siberia and Mongolia. In the Levant it is found in Lebanon and Israel.

These moths mainly inhabit deciduous forests, hedgerows, parks and gardens, at an elevation up to 1,600 metres (5,200 ft) above sea level.[2]

Acronicta psi has a wingspan of 34–45 mm (1.3–1.8 in).[3] These moths have grey forewings with bold black dagger-shaped markings. (The Latin specific name also refers to these markings, as resembling the Greek letter psi, ψ.)[3] The hindwings are dirty grey, generally paler in the male.

The moth is very similar to the dark dagger (Acronicta tridens) and identification is generally only possible by minute examination of the genitalia.[3] See Townsend et al.[4] 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. Moreover, the larvae of the two species are very different.

Figures 2, 2a, 2b show larvae after their final moult

The larva of Acronicta psi is quite hairy, greyish or brownish below and black above, with red spots along the sides and a bold yellow stripe along the back. It has a distinctive horn just behind the head (absent from the larva of dark dagger).

The grey dagger flies at night from June to August[lower-alpha 1][3] and is attracted to light and sometimes to sugar.

It feeds on a wide range of plants, mainly trees and shrubs (see list below). The species overwinters as a pupa.

Recorded food plants include:[5]

• 
  Half-grown caterpillar of Acronicta psi feeding on Rosa canina
• 
  Mature larva feeding on a Japanese cherry tree in early autumn
• 
  Mature larva in early autumn
• 
  Pupa
• 
  Imago. Mounted specimen

• 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

Wikispecies has information related to Grey dagger.

Wikimedia Commons has media related to Acronicta psi.

• Lepiforum.de (in German)
• Paolo Mazzei, Diego Reggianti, Ilaria Pimpinelli Moths and Butterflies of Europe and North Africa
• Svenska fjärila (in Swedish)