Plain Pug Eupithecia simpliciata
Wingspan 21-23 mm.
Despite its English (and Latin) name, this is one of the more distinctively-marked Pug moths, and is relatively easy to identify.
It flies from June to August, and frequents waste ground, saltmarshes and other tidal or coastal habitats. It is found throughout most of England, though scarcer further north, and is local in Ireland and Wales.
The caterpillars feed on the seeds of orache (Atriplex) and goosefoot (Chenopodium).