Size: 8 to10 mm. The abdomen is black without a band of reddish-yellow on the middle segments. The third antennal segment is clearly shorter than the scape and about the same length as, or less than, segment four. Scutellum yellow. Antennal scape dark marked at the base of the inner side. Head usually with conspicuous yellow spots behind each eye.

Unless identified by a recognised expert, a photo is required. If the photo doesn't show the key ID features, then in the comments box describe the size and identifying characters you have observed.

Hedgerows where Hawthorn or Blackthorn are present. Also found on Rowan, Prunus etc.

Flight period: April to July.

Pamphilius sylvaticus larvae are associated with Hawthorn, Blackthorn and several broadleaved tree species. They create a leaf-roll and feed within.

Widespread in Britain. This is the commonest species in this genus, and found as far north as northern Scotland.

Status in Leicestershire and Rutland not known.

https://www.sawflies.org.uk/pamphilius-sylvaticus/