Wax-tail hoppers belong to the family Fulgoridae, and are distant relatives of cicadas and treehoppers. Like their cousins they also feed on plant juices (floem mostly), extracted through their long, siringe-like mouthparts. Plant juices are rich in carbohydrates, and wax-tails convert them into ketoester waxes, which are used to produce long, feather-like plumes. Their main function appears to be mostly defensive, both against large predators, who are likely to end up with a mouthful of wax rather than a tasty insect, and against small parasitoid insects. Females also use the wax to cover their egg clutches to protect them from parasitoids and desiccation.
After the female had finished laying her eggs, I moved her, very gently as not to break off her “tail”, onto the white background of my portable field studio. Incidentally, if you ever need to photograph a white or translucent insect, place one of the lights above the insect and only slightly behind. If the light is directly behind then the white elements of its body will not show very well or disappear completely.