Ant hair is about 98% reflective, and is very similar to how fiber optics work. SEM images in the link for fellow nerds.

On shaving ants:

Speaking to MailOnline, Willot confirmed this ‘was indeed a tricky procedure. They are very reactive and won’t stop struggling once caught, preventing any shaving attempt if not anaesthetised.’

This was done by exposing the ants for a few seconds to carbon dioxide, then strapping them down firmly.

Hairs were removed using a high-power binocular telescope and a very sharp blade.

‘It’s the same as shaving your own chin: the scalpel blade has to move in the opposite direction of the hair’s growth. It has to be a delicate and gentle motion,’ said Willot.

After practising on large soldier ants, he found that a smaller worker ant could be entirely shaved in an hour of delicate work.

He estimates around 40 ants were shaved altogether to produce seven good examples for the experiments.