Its flight period is much more restricted, the Chestnut can be caught in almost any month of the year and I catch it regularly from September to May whereas the Dark Chestnut generally flies between late September and December.
The main features to separate the two are the dark brown/ chocolate colouring and straighter forewing of the Dark Chestnut with a squarer end to the wing. The pale marks on the edge of the wing towards the tip tend to be more prominent in Dark Chestnut. There is considerable variation in both species and consequently these features overlap somewhat.
I caught another Large Wainscott last night in a catch of 19 moths of 9 species which included another Silver Y. These are good numbers for the time of year for me.
|Chestnut and Dark Chestnut|