003 Blastobasis lacticolella

BLASTOBASIDAE

41.003 Blastobasis lacticolella (Large Pale Masoner)

ws 13-22mm; Jun-Jul, Sep-Nov; common throughout UK.
Synonym: Blastobasis decolorella (MBGBI4.1)

Blastobasis lacticolella §1 male

ID: See B.adustella vs B.lacticolella for more detail
Very variable but individuals with heavy fuscous irroration should be B.adustella, while pale individuals with an indistinct dorsal strigula should be B.lacticolella (especially when fw>9.0mm)
Male genitalia: Uncus broadest at base and tapers towards apex
Female genitalia: Ratio of length of posterior apophysis to anterior apophysis >2.5

§10 is well outside the quoted size range for B.adustella with fw 10.9mm. If the female genitalia distinctions are reliable, these confirm its identity as B.lacticolella - but it shows heavy fuscous irroration of forewing, labial palps and abdomen - suggesting that all these features favouring B.adustella are unreliable, though it does leave open the possibility that heavy fuscous irroration of the forewing proximal to the dorsal strigula could be a good feature for B.adustella.

Variation
Dissection
Male genitalia
Female genitalia

§1 Westcliff-on-sea, Essex; 31/05/2009; male; fw 7.4mm
§2 Foulness, Essex, 08/07/2007; male
§3 Westcliff-on-sea, Essex, 04/10/2007, fw 8.3mm
§4 Thursley Common, Surrey; 16/06/2008; male; fw 9.5mm
§5 Westcliff-on-sea, Essex; 18/06/2008
§6 Westcliff-on-sea, Essex, 02/07/2008, fw 8.6mm
§7 Sutton Fen, Norfolk, fw 9.0mm
§8 Foulness, Essex; 27/09/2009; female
§9 Foulness, Essex; 27/09/2009; male; fw 8.2mm
All images © Chris Lewis

§10 Strumpshaw Fen, Norfolk; 07/07/2013; female; fw 10.9mm
§11 Dodd Wood, Cumbria; 12/11/2014; male; fw 8.6mm
§12 Bampton Grange, Cumbria; 14/06/2017; female; fw 9.0mm
§13 Stour Wood, Essex; 06/06/2021
§14 ??;??/06/2022; female; fw 10.1mm