Spider and the Fly

Looking at the Spider Plant this morning some of the Hoverflies are looking in the wrong place for the nectar on the flowers.
The flowers that were attracting the flies yesterday are not producing the sweet fluid which exudes from the tips of the long spidery filaments. I presume they have been pollinated and so don't require the attentions of the obliging Flies.
The Flies must need to smell the nectar to be guided to it, they seem to be looking at the base of the petals where in many plants it is the source of the nectar.