The Rosy Underwing is superficially similar to the native Red Underwing but is slightly smaller and paler looking. Comes to sugar and sometimes to light.
No evidence of breeding in the British Isles but in Europe, the caterpillars can be found between May and June.
There are less than two dozen records from the UK with the first from Shoreham, Sussex in 1875. First recorded on the Channel Islands in 2002 where it is now thought to be resident.
Flies from July to September in one generation, immigrants to the UK can be seen from August.