Larvae and adults are relatively poorly repelled by aldehydes (Rodrigues, 1980; benzaldehyde usually employed in the relevant Y-tube/olfactometric tests); strongest allele, in this regard is olfA^x1 and yet it still detects these odorants (Ayyub et al., 1990). Responses to ethyl acetate, acetone, acetic acid and ethanol are normal (first of these tested in adults and larvae, the latter three only in larvae). In odor-induced jump assay, mutants show about half-normal frequency of such responses (Ayyub et al., 1990). Electroantennogram recordings from adults indicate somewhat reduced response to benzaldehyde, but normal ones to butanol and butyl acetate (Venard and Pichon, 1984). The physiological defect seen, with benzaldehyde as the stimulus, involves a biphasic dose-response curve (Venard et al., 1989), as if there are two kinds of antennal receptors for this substance, only one of them being affected by olfA.

Original group of these mutations reported initially by Rodrigues and Siddiqi (1978), but not then noted as 'olfA' (see Rodrigues, 1980 and subsequent references). olfA alleles complement the closely linked olfC and olfE mutations.