Scientific name: Synanthedon scoliaeformis
Late June – July. A very local species known only from north and mid Wales, central Scotland, south-western Ireland and two sites in England. A black wasp-mimic with an orange tail fan. Frequents old birch trees growing in open situations.
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
- UK BAP: not listed
- Priority Species in Wales (‘Section 42’ list)
- Red Data Book
Particular Caterpillar Food Plants
Downy Birch and Silver Birch
- 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).
Hillside pastures with scattered old birch trees. Also in open birch woodland and on wooded heathland.