The alder moth (Acronicta alni) is a moth of the family Noctuidae. It is found in Europe (from southern Fennoscandia to Spain, Italy and the Balkans), Turkey, the European part of Russia and the neighbouring countries, the Caucasus, the Ural, southern Siberia, Transbaikalia, the Russian Far East (Primorye, Sakhalin, southern Kuriles, Khabarovsk and the Amur region), China, Japan (Hokkaido and Honshu) and the Korean Peninsula.


Acronicta alni


Caterpillar


Caterpillar on leaf

The wingspan is 33–38 mm. Forewing pale grey; inner margin and a broad median shade black; hindwing white.In the ab. steinerti Cusp, the ground colour is dark brownish grey; ab. carola Phil, representing an intermediate form; in ab. suffusa Tutt the two pale patches are as dark as the rest of wing; in ab. obsoleta Tutt the orbicular stigma is wanting.

The adults fly at night from May to June and are attracted to light.

The larva when young resembles a bird dropping at first. When mature the larva is black and yellow with a number of hairs. It feeds on a number of different trees, particularly alder and birch.