071 Acleris emargana

TORTRICIDAE | Tortricinae: Tortricini

49.071 Acleris emargana (Scalloped Tortrix)

ws: 16-22mm; Jul-Sep; sallow (Salix spp), poplar (Populus spp), birch (Betula spp); common in woodland throughout GB
Synonym: Rhacodia emargana (Pierce and Metcalfe)

Acleris emargana §5 male form caudana

ID: A.emargana and A.effractana are both characterised by having a distinct costal concavity. In A.effractana the costal concavity is shallower. The forewing may also show groups of raised scales - in A.effractana these are blackish, while in A.emargana they are whitish. The two species are both quite variable and similar enough that genital determination is required for confident ID.
Male genitalia: The socii of A.effractana are longer than those of A.emargana. In Acleris species the central projection of the tegumen is the anal tube which in both A.effractana and A.emargana is well-developed, highly chitinised and extends beyond (posterior to) the posterior border of the uncus. The uncus itself is relatively weak, bifid and is partly obscured by the anal tube in the standard slide preparation*. In A.effractana the socii extend beyond the apex of the uncus to be more or less level with the apex of the anal tube; in A.emargana the socii extend roughly to a level with the posterior border of the uncus and not as far as the apex of the anal tube.
*It is clear that neither Moth Dissection nor the authors of MBGBI5.1 have understood this - the anal tube is labelled as the uncus in the illustration showing the difference between these species on p36 of MBGBI5.1.
Female genitalia:

Variation
Dissection
Male genitalia
Female genitalia

The socii extend roughly to a level with the posterior border of the uncus (B) and not as far as the apex of the anal tube (A)

§1 Strumpshaw Fen, Norfolk; 09/09/2011; male; fw 9.5mm; form caudana
§2 Barra, Outer Hebrides; 14/09/2017; male; fw 8.8mm; form griseana
§3 Arrochar, Argyll; 15/09/2017; male; fw 9.1mm; form emargana
§4 Orlestone Forest, Kent; 26/07/2018; male; fw 8.9mm; form caudana
§5 Pound Wood, Essex; 27/08/2019; male; fw 8.9mm; form caudana
§6 Bowness-on-Solway, Cumbria; 28/07/2020; fw 8.1mm; form caudana
§7 Orlestone Forest, Kent; 12/08/2020; female; fw 10.2mm; form emargana
§8 Pound Wood, Essex; 12/08/2022; form caudana
§9 Fingringhoe, Essex; 01/08/2024
All images © Chris Lewis