A distnctive species which has a unique mark amongst moths on its forewing, hence its name. The mark maybe variable, as can the forewing ground colour. Wingspan 30 to 35mm.
The adults fly March to early May in the south of Britain, and April to early June in the north and Ireland. They are found in various habitats, from moorland to gardens. Common and widespread throughout.
I came across the larva near my local pond feeding on sedge. It feeds mainly at night in April to July, feeding on the buds at first and then the leaves. It feeds on a wide range of vegetation, including trees, shrubs and herbaceous plants. It overwinters as a pupa in a cocoon underground, with the fully formed adult inside it.
Adult photographs taken in March 2014, rear garden, and larva in June 2011, near local pond, Stafforshire, England.