009 Caloptilia robustella

15.009 Caloptilia robustella (Shaded Oak Stilt)

ws:10-13mm; bivoltine - mid-Apr-May, Aug; oak (Quercus spp); common in SE.England, less common elsewhere.

Calptilia robustella §6 female

ID - Key: Labial palp with S2 not tufted; clear well-defined yellow costal blotch; terminal cilia distinctly paler than ground colour > C.robustella or C.alchimiella.
MBGBI2 gives a table of features for separating these two - features for C.alchimiella are given first:

Head - vertex purplish brown, darker than thorax (vs) vertex ochreous concolorous with thorax
Thorax - golden-yellow, tegulae pale purple brown (vs) ochreous, including tegulae
Forewing basal blotch - sharply defined (vs) diffuse
Forewing costal blotch - outer angle produced along costa almost to apex (vs) not or hardly produced along costa towards apex
Forewing tornal spot (yellow) - minute (vs) absent

Male genitalia: Aedeagus - many small cornuti in two rows near base, single irregular row near apex (vs) 6-7 large cornuti in two rows
Female genitalia: Ductus bursae - even width with evenly dispersed granulation (vs) narrows gradually towards bursa and abruptly towards ostium, granualtion strongest on one side at widest section of ductus.

Variation
Dissection
Male genitalia
Female genitalia

§1 Westcliff-on-sea, Essex; 31/07/2010; male; fw 5.0mm
§2 New Forest, Hampshire; 03/06/2012; female; fw 5.3mm
§3 Westcliff-on-sea, Essex; 10/08/2013: male
§4 Hockley Woods, Essex, 12/05/2014; male; fw 5.1mm
§5 New Forest, Hampshire; 15/05/2018; male; fw 5.1mm
§6 Pound Wood, Essex; 20/05/2020; female; fw 5.4mm
All images © Chris Lewis