Generally referred to as one of the ‘dagger moths (so-called because - using your imagination! - the long, black shape passing inwards from the lower corner of the forewing resembles a dagger!), Acronicta alni, the Alder moth, is not a common species in the U.K., but is reported to be more likely to be observed flying during the months of May and June in the New Forest, Hampshire, and in some of the woodlands in Sussex.
The most striking period of the moth’s life cycle is the larval stage which uses a two-stage approach to predator avoidance. The grey, black and white colours of young larvae are camouflaged to look like bird droppings but, as they mature, the larvae take on black and yellow bands as warning colouration (for other examples of this warning colouration eg the Common wasp and Cinnabar moth larva, see the Collections website). Hairy spines are present along the length of the larvae, and long, club-like hairs are associated with most of the yellow stripes (the hairs are said to cause an itchy rash if the larva is handled).
Although alder and birch trees are a popular food source for the larvae, they feed on most trees and bushes during summer and early autumn.
