The Riband Wave -- wingspan 23-30mm; UK flight time Jun-Sep.
The Riband Wave moth has a delicate sheen in flash light but looks quite drab in daylight. Above is the plain form.
Another form has a dark band between two of the lines - a "ribboned" wave. Both forms are equally common.
I had thought initially that this moth might be a PLAIN WAVE (Idaea straminata)
moth which looks a little similar to the plain form of its cousin the Riband Wave, but has a lighter background colour, gentler lines and is lacking the strong border line on the back edge of the wings, having just a faint suggestion of the border and the dots. However, it is a pale RIBAND WAVE, the giveaway being the shape of the lower line near the leading edge of the wing: -- on the Plain Wave it is a smooth gentle curve rather than an angular line. They are very similar.
The background and lines on the Plain Wave are a little darker than its other cousin the
Common White Wave
, which doesn't have the border edging.
(With a Latin name like "idea," should be called "brain wave".)