73.331 Diarsia dahlii (Barred Chestnut)
fw: 15-18mm (Waring & Townsend), ws: 32-42mm (MBGBI9); Aug-Sep; various woody and herbaceous plants; local in N.England, Wales and Scotland, rare in S.England
Diarsia dahlii (Barred Chestnut) §5 male
ID: Male: Forewing broad with a strongly curved costa; ground colour orange-brown to reddish brown; oval and kidney marks fairly inconspicuous; usually a diffuse and irregular darker median fascia between oval and kidney marks and a darker subterminal fascia. Female forewing narrower than male though still with an arched costa; dark reddish-brown to dark purplish-brown; kidney mark usually conspicuous pale brown. A pale wavy subterminal line is usually the most conspicuous crossline in both sexes.
Males may be similar to D.mendica (Ingrailed Clay) which has a straighter costa and usually shows black quadrate marks between the antemedian line and oval and between oval and kidney marks; the hindwing is also paler in D.mendica ("pale grey-brown" vs "greyish-brown").
Females are more similar to D.brunnea (Purple Clay) which has a dark postmedian fascia, lacks the pale subterminal line and usually shows a quadrate black mark between oval and kidney.
Males may be similar to D.mendica (Ingrailed Clay) which has a straighter costa and usually shows black quadrate marks between the antemedian line and oval and between oval and kidney marks; the hindwing is also paler in D.mendica ("pale grey-brown" vs "greyish-brown").
Females are more similar to D.brunnea (Purple Clay) which has a dark postmedian fascia, lacks the pale subterminal line and usually shows a quadrate black mark between oval and kidney.
§1 Patterdale, Cumbria; 17/08/2008; male; fw 17.6mm
§2 Aberfoyle, Perthshire; 19/08/2008; female; fw 17.5mm
§3 Aberfoyle, Perthshire; 21/08/2008; male; fw 16.8mm
§4 Loch Rannoch, Perthshire; 24/08/2008; female; fw 17.6mm
§5 Dalmunzie (Glenshee), Perthshire; 30/08/2016; male; fw 16.1mm
§6 Dalmunzie (Glenshee), Perthshire; 31/08/2016; male; fw 16.0mm
§7 Loch Fyne, Argyll; 29/07/2022; male; fw 16.6mm
§8 Loch Fyne, Argyll; 03/08/2022; male; fw 19.1mm
All images © Chris Lewis
§2 Aberfoyle, Perthshire; 19/08/2008; female; fw 17.5mm
§3 Aberfoyle, Perthshire; 21/08/2008; male; fw 16.8mm
§4 Loch Rannoch, Perthshire; 24/08/2008; female; fw 17.6mm
§5 Dalmunzie (Glenshee), Perthshire; 30/08/2016; male; fw 16.1mm
§6 Dalmunzie (Glenshee), Perthshire; 31/08/2016; male; fw 16.0mm
§7 Loch Fyne, Argyll; 29/07/2022; male; fw 16.6mm
§8 Loch Fyne, Argyll; 03/08/2022; male; fw 19.1mm
All images © Chris Lewis
Page published 03/02/2017 (§1-6) | §7&8 added 22/12/2022
