The adults of Grey Dagger (Acronicta psi) and Dark Dagger (Acronicta tridens) cannot be readily distinguished and records should be added as an aggregate unless identification by genitalia dissection has been undertaken. The caterpillar stage is not a problem as the species are quite different.

Adults fly in June and July.

Both species appear to be widespread in Britain although true status is difficult to determine due to the difficulty of identification.

NatureSpot records for the caterpillar stage suggest that Grey Dagger - Acronicta psi is the more common of the two species in our area.