Adults: Small black sawflies 3.7 mm long. All black except for small amounts of white on each femur, tibia and tarsus. Wings with light brown banding and darker near the body. Antennae shorter than thorax (longer in Fenusa dohrnii). The larvae mine the leaves of Birch producing a blotch on the upper side of the leaf. It starts near the midrib and extends outwards towards the leaf edge. The larvae have four spots - the anterior spots (those near the head on the underside) being large (as shown) which distinguishes it from P.thomsoni.
Where Birch is present.
The larval mines can be seen when Birch is in leaf.
Status in Britain is difficult to determine due to lack of records.
Rare or under recorded in Leicestershire and Rutland. The Fosse Meadows record of 3rd October 2018 is thought to be the first for VC55.
Leicestershire & Rutland Map
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Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015