Catoptria permutatella might give you the impression of being quite easy to identify. But alas, it has a few very similar brothers. By day you'll not find it in the grass, for it doesn't rest there at all. Rather you should be looking at tree trunks, fences or even walls. In nature it rests on trees, especially isolated birches and pines. Even though it may look like other Grass Moths, it's caterpillar feeds on mosses by exception. Rare in Britain, where it is only found in a few glens in Perthshire and Aberdeenshire (Barry Goater, 1986). More common on the continent, but still usually a rather local species.