|
TORTRICIDAE | Tortricinae| Cochylini
|
49.124 Aethes francillana (Narrow-barred Straw)
ws: 13-18mm; Jun-Sep; wild carrot (Daucus carota); local on downland and waste ground throughout GB, predominantly coastal further north.
Aethes francillana §3 female
Male genitalia: The difference between the 2 species is quite striking in the male genitalia. The sacculus of A.francillana is deeply emarginate and produced into a squared arm; while in A.beatricella the margin is a smooth curve. The transtilla (see image right) of A.francillana is deeply indented to form a pair of pointed arms; while in A.beatricella it has a small central notch.
|
ID: Both A.francillana and A.beatricella have complete median and postmedian fasciae and they appear very similar. In A.francillana the fasciae are narrower and more oblique. The fasciae in both species are of uneven width so the statement that they are narrower in A.francillana is based on an eyeball impression of the average width and identification of an individual on this basis may require comparison with other examples of both species. BTM states that in A.francillana "the costal end of the median fascia extends beyond the dorsal end of the postmedian (fascia)". In theory this should provide an absolute distinction between the 2 species. However, assessment of it depends on getting the costa exactly horizontal (difficult to achieve reliably on a live specimen) and since the costa itself is not entirely straight this is problematic. There is a straight section of costa in both species (horizontal blue line on images opposite). A perpendicular line (green in images) drawn from the distal margin of the costal end of the median fascia cuts the dorsum just beyond the distal margin of the dorsal end of the postmedian fascia in A.francillana and within the dorsal end of the postmedian facia in A.beatricella.
|
§1 Foulness, Essex; 26/07/2009; male; fw 7.0mm
§2 Portland, Dorset; 19/06/2015; female; fw 6.9mm
§3 Foulness, Essex; 08/08/2020; female; fw 6.8mm
§4 Portland, Dorset; 29/08/2023; male; fw 6.9mm
All images © Chris Lewis
§2 Portland, Dorset; 19/06/2015; female; fw 6.9mm
§3 Foulness, Essex; 08/08/2020; female; fw 6.8mm
§4 Portland, Dorset; 29/08/2023; male; fw 6.9mm
All images © Chris Lewis
Page published 25/04/2012 (§1) | §2 added 25/02/2016 | §3 added 05/02/2021 | §4 added 27/12/2023
