Plain Wave Idaea straminata
Wingspan 28-33 mm.
Care has to be taken with the identification of this species, as it closely resembles the remutata form of Riband Wave, (Idaea aversata) although the latter has a more angled outer cross-line near the wing tip.
It is widely distributed throughout Britain, but relatively uncommon.
Like many of its close relatives, the larvae feed on dandelion (Taraxacum) and knotgrass (Polygonum).
It is single-brooded, flying in July.