Metallus pumilus

The larva of the sawfly Metallus pumilus mines the leaves of various Rubus species including Brambles. The mine begins with a short, quickly widening corridor which opens into a large, very transparent, almost full depth blotch that often overruns the initial corridor. The larva has a large prothoracic plate, two further thoracic spots and one spot on the first abdominal segment (this distinguishes it from M.albipes).  It is necessary to check the larva or rear through in order to identify to species level.

Metallus albipes leaf mines.  Some Nepticulidae moths form blotch mines on brambles and related species, but have not been recorded in VC55

Adult Leafmine

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

Where the host plants (Rubus sp.) are present.

Adult: May and June.  Leafmines in June, July and September.

The three species of the sawfly genus Metallus are reputedly rare in the UK, though this may be down to under recording.  Metallus pumilus appears to be widespread but rather uncommon based on the few records available.

Rare or under recorded in Leicestershire and Rutland. The Stoney Stanton record of 22nd September 2018 is believed to be the first for VC55.

http://www.leafmines.co.uk/html/Hymenoptera/M.pumilus.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/hymenoptera/symphyta/tenthredinoidea/tenthredinidae/heterarthrinae/metallus/metallus-pumilus/

https://www.sawflies.org.uk/metallus-pumilus/