Description: Wingspan 38-44mm. Adults are single-brooded and variable in colour and pattern although individuals of this species tend to be lighter. Date of capture is a contributing factor in determining identification (see Engrailed). Generally from the beginning of May to the end of June, occasionally early July.

World Distribution: Across Central Europe.

Irish Distribution: Widespread across southern counties, sporadic further north. More commonly encountered than the scarcer Engrailed E. bistortata. Recorded frequently from well-trapped localities such as, Belvoir Park and Lackan Bog Down, also Annagarriff Wood and Brackagh Moss Armagh and Crom Estate, Florencecourt and Monawilkin Fermanagh.

Ecology: A species normally associated with woodland, bogs, limestone uplands and other scrubby areas. Adults unlike the Engrailed are not as attracted to light and seldom appear in any numbers. The larvae can be found in July and August on birch Betula spp., larch and willow Salix spp. It overwinters in the pupal stage.

Key Identification Features:

• Ground colour is usually a pale whitish brown with well-defined crosslines, which are frequently edged with yellow
• Date of capture important when making identification.

Distribution Map from NBN: Ectropis crepuscularia at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Ectropis crepuscularia at iNaturalist World Species Observations database.