Willow Mason-wasp

Symmorphus bifasciatus


Body length 6.5 - 9.5mm. A black wasp with yellow marks on the thorax and two yellow bands on the abdomen.


Woodland edge, parks and gardens. The female seeks out hollow stems to stuff with the larvae of small leaf beetles, particularly the Blue Willow Beetle, before she lays an egg and seals the hole.

Status and distribution

Fairly common and widespread though out southern Britain and also in lowland Scotland. Fairly common in Nottinghamshire and at Netherfield Lagoons.

Best time to see

May to August.