Because of the sometimes considerable variation within most saltmarsh inhabiting Scrobipalpa species, identification by wing markings alone will often not be possible. Caution and care are the watchwords for this group.
S. salicorniae is best identified by dissection but breeding through from one of the known foodplants will greatly assist in the process of naming the moth.
When encountering specimens which are smaller than usual or have less extensive dark markings on the wing, particularly those found on the east or south-east coast of England, it may be worh considering the possibility of two additional species found in France. S. spergulariella is associated with Spergularia media (greater sea-spurrey) and is generally smaller at 9-12mm (as opposed to 13-15mm for S. salicorniae). S. halimoniella is intermediate in size betwen these two (at 11-14mm) and feeds on Atriplex portulacoides (sea-purslane). This species has generally plain light grey-brown forewings almost without distinct black markings. Dissection will be an essential part of the identification process should either of these moths be suspected.
More generally with the coastal Scrobipalpa species, if a moth has been bred from a known foodplant, and therefore by inference the time of year when the larva feeds and the nature of its feeding methods have been observed, this information, plus a freshly emerged moth, will allow the number of possibilities to be reduced. If the bred or caught moth is a fresh specimen AND displays the distinctive markings of some species (see below) then an identification without more detailed examination should be possible in many cases.
Those more readily identifiable when freshly emerged by the forewing markings are listed below. However all of these also have variation in their wing markings which, when the obvious features are obscured or worn, will then resemble some other Scrobipalpa species.
Scrobipalpa suaedella - those with an obvious clear pale ochreous dorsal quarter to the forewing.
Scrobipalpa obsoletella - those with the forewing a pale greyish colour lacking any red-brown colouration and appearing paler in the final one-third due to a pale postmedial fascia.
Scrobipalpa ocellatella - those with the prominent angled fascia at three quarters on the forewing and dark markings contrasting with the surrounding paler ground colour.
In cases where there is any doubt, particularly where worn light-trapped specimens are concerned, dissection will be essential to obtain an accurate identification until a good familiarity is built up with the range of species and their markings at a particular site.
Even genitalia differences are often small but are constant between the various species. It is advisable to seek confirmation of identifications by genitalia until familiarity is built up with this genus.
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