Fenusella nana

Description

The larvae of the sawfly Fenusella nana mine the leaves of various Birch (Betula) species. The mine starts at the tip of a vein at the leaf edge and a triangle or plug of frass is left at the start of the mine which takes the form of a large pale blotch. The larva is initially green and then turns a dark yellow colour towards maturity.

Identification difficulty

Adult Mine larva should be checked and photographed if possible.

Recording advice

Adult: Unless identified by a recognised expert, a photo is required and the specimen should be examined with a microscope. In the comments box, state the key or ID method used and describe the size and identifying characters.  

Leafmine: 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. The larva should be checked and photographed if possible.

Habitat

Where Birch is present.

When to see it

Mines may be found when Birch is in leaf.

Life History

Pupation occurs outside the mine.

UK Status

The species seems to be widespread in England and Wales but is not well recorded.

VC55 Status

Status in Leicestershire and Rutland not known.

Leicestershire & Rutland Map

MAP KEY:

Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map