A fairly large clearwing moth, which is mostly black with two narrow yellow bands on the abdomen. The tail fan is a striking feature, being large and orange in colour. The caterpillar feeds for several years on the inner bark of old birch trees.

The moth flies by day but is very rarely seen, though it can be attracted to a specific pheromone lure in sunny weather.

A better way to record the moth is to look for 5mm-diameter holes on birch trunks, which are made by the moth as it emerges from the pupal cocoon located beneath the bark. The holes persist for several years and can be found year-round, but are best looked for in late summer when the yellow-brown pupal case (exuviae) often remains protruding from the hole. The pupal case provides confirmation that a hole was made by Welsh Clearwing and not another wood-boring insect. Longhorn beetles also make holes in birch trunks, although these usually frequent decaying wood whereas Welsh Clearwing uses only living tissue.

Size and Family

  • Family - Clearwings (Sesiids)
  • Medium Sized 

Conservation status

  • UK BAP:  not listed
  • Priority Species in Wales (‘Section 7’ list)
  • Red Data Book

Caterpillar Food Plants

Downy Birch and Silver Birch

Habitat

Hillside pastures with scattered old birch trees. Also in open birch woodland and on wooded heathland.

Distribution

  • Countries – England, Wales, Scotland and Ireland
  • In Wales occurs mainly in southern Merionethshire and northern Montgomeryshire, with more isolated populations further south in Montgomeryshire and in Radnorshire and Breconshire. Also occurs in central Scotland (Perthshire, Inverness-shire and Sutherland), south-western Ireland (County Kerry) and at two recently-discovered sites in central England (Cannock Chase and Sherwood Forest).
Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing - Iain Leach

Welsh Clearwing

Welsh Clearwing (pupa case) - S.Lewis

Welsh Clearwing (pupa case)

Welsh Clearwing (exit-hole) - S.Lewis

Welsh Clearwing (exit-hole)