Fenusa pumila

Description

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 black spots underneath - the anterior spots (those near the head on the underside) being large (as shown) which distinguishes it from Profenusa thomsoni.  The feet are relatively long and slender. In the final pre-pupal instar, pigmentation is lost

Similar Species

Several other sawflies mine birch leaves.  

Identification difficulty

Adult Leafmine (when host plant is identified)

Recording advice

Leaf mine photographs should be backlit so that the frass patterns and larva can be seen.  The host plant must be identified in the comments

Habitat

Where Birch is present.

When to see it

The larval mines can be seen when Birch is in leaf.

UK Status

Status in Britain is difficult to determine due to lack of records.

VC55 Status

Probably quite frequent but 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

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2025+ | 2020-2024 | pre-2020

UK Map

Species profile

Species group:
Sawflies
Kingdom:
Animalia
Order:
Hymenoptera
Family:
Tenthredinidae
Records on NatureSpot:
17
First record:
03/10/2018 (Calow, Graham)
Last record:
30/08/2024 (Calow, Graham)

Total records by month

% of records within its species group

10km squares with records

The latest images and records displayed below include those awaiting verification checks so we cannot guarantee that every identification is correct. Once accepted, the record displays a green tick.

In the Latest Records section, click on the header to sort A-Z, and again to sort Z-A. Use the header boxes to filter the list.

Latest images

Latest records