The usual dark form of B. umbrosella superficially resembles Eulamprotes atrella, Aproaerema anthyllidella and Syncopacma sangiella, particularly if it is lacking or only has one bright white scale in the centre of the forewing. All three are larger, longer-winged moths and always have a slight yellowish or ochreous tinge to their pale scales. Even when faded or slightly worn, it is still usually possible to see the single or small group of pure white scales in B. umbrosella just beyond the prominent black spot in the fold (the lowest of the three black spots nearest the base of the wing).
The clear white costal and tornal patches contrasting with the almost black forewing readily separate it from B. affinis and B. similis, but when these white markings are muted or absent, dissection may be necessary.
The light forms of B. umbrosella can have the forewing ground colour greyish (f. portlandicella) to whitish (f. mundella) whereas pale forms of B. affinis are ochreous to brownish.