Stigmella roborella

Diagnostic description: 

Diagnosis. Male S. roborella can be recognised by the combination of a pale head, uniform forewings, and hindwings with a not very distinct cover of pale brown androconial scales. S. eberhardi has usually much darker (bronze brown) androconials, and S. svenssoni and szoecsiella have grey hindwings without androconials. Moreover, S. svenssoni has special scaling on the forewing underside. The rare pale-headed form of S. samiatella is particularly confusing, since it resembles S. roborella closely. Females resemble all the other pale-headed species, but S. roborella is the only one with a more or less pointed abdominal tip (ovipositor); it has more antennal segments (28-31) than S. ruficapitella, dorsiguttella or szoecsiella (23-27) and fewer than S. suberivora or ilicifoliella (33-40). In southern localities, especially Sicily (where S. eberhardi has not yet been found), the androconial scales may be as dark as in eberhardi, making it impossible to separate the species on externals.
Male genitalia are characterized by a pointed inner lobe of the valva, resulting in a valva with two pointed tips, and the slightly curved vesica with three groups of cornuti, although less distinct than in the similar S. eberhardi. The vinculum is very variable in the length of the ventral plate. Female genitalia characterised by the single coil and the spines in posterior part.

Associations: 

Hostplants. Quercus cerris (Szöcs 1977), Q. petraea, Q. pubescens, Q. robur, Q. rubra [incidentally].
Leafmine. A long gallery, often with straight parts, with frass usually in a narrow line throughout, occasionally slightly widened in second part. Egg on either side of the leaf, although Borkowski (1972) only mentioned upperside; usually against a vein. Larva yellow, pale headed (see photograph in Huisman et al. 2001). Mine similar to that of S. eberhardi, atricapitella and dorsiguttella. Cocoon: red brown to dark brown. 

Distribution: 

Throughout Europe, also in Southwest Asia, common almost everywhere, but fewer records in the Mediterranean countries. Since its description in 1971, positively recorded from most European countries (Borkowski 1972, Budashkin 1988, Gielis & Hull 1975, Johansson 1971, Johansson & Nielsen 1990, Karsholt & Nielsen 1976, A. & Z. Laštuvka 1990, 1991, 1997, Z. & A. Laštuvka 1998, Lo Duca et al. 2002, Puplesis 1994, Sulcs & Sulcs 1989, Szöcs 1977), except Albania, Belarus, Bosnia, Bulgaria, Ireland, Moldova, Portugal, Romania or Yugoslavia. New records for Georgia, Macedonia and Turkey. One of the few species on Mediterranean islands: Sardinia and Sicily. Highest altitude: 1500 m in Spain.

Life cycle: 

Life-history. Bivoltine, larvae in June-July and September-November, adults from April-September, usually somewhat later than S. ruficapitella.

Citation: 

This taxonomic description is based on Van Nieukerken (2003).

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith