Microdon dubius flowers may be just yellow as here. The swan-neck flower tubes present the flower mouths in a welcoming outward-looking posture after staying close to the stem in their base parts. (Always accommodate your service providers!)
Pretty in day-time, the flowers announce a strong nocturnal presence via their fragrance. Moths being important night-time pollinators, are well served by this. They presumably find the other, darker coloured flower forms of this plant by following the scent equally well as bees do colours and shapes. Otherwise those flowers might have disappeared from not matching the pale ones in the survival stakes. The short green flower bracts are notable around the corolla tube bases.
The epithet, dubius, meaning doubtful (Latin) was already given to this plant by Linnaeus in his 1753 book. Although a great traveller, he never visited South Africa and was thus dependent upon many with naturalist inclinations that visited the Cape in olden days (particularly Thunberg), bringing or sending plant samples to Europe (and some to him).
Linnaeus wasn’t sure as to where this plant fitted into the plant family tree, hence this specific name. Even the greatest don’t know everything; the network of collective, accumulative effort being the strength in knowledge. Knowledge grows best when people communicate and collaborate across social borders. Conflict makes spying necessary (www.phillipskop.co.za).