A common and extremely variable species, mainly in its ground colour, which varies from pale to dark. The flight period is from July to August over grasslands, scrub and gardens. The larvae feed on various grasses. This is almost identical to lesser common rustic (Mesapamea didyma) and although there is a size difference in many specimens (as the name suggests), there is too much overlap to use it as a reliable character in identification. Therefore, we have retained Mesapamea secalis agg. for recording purposes where determination by genitalia examination has not been conducted.

References: 
Leverton, R. & Cubitt, M. (2024). The Larger Moths of Scotland.
Waring, P. & Townsend, M. (2018 third edition). Field Guide to the Moths of Great Britain and Ireland.