Are the sandflies all over in large amounts or so they only appear in certain parts along the track.
Can anyone recomend any insect repellents that are ok to your on sensitive skin?


Depends what time of the year.
Winter tends to kill a lot of 'em off but yeah....the whole of fiordland including the Routeburn/Hollyford is notorious.
OFF! makes a sensitive skin formula.
Sandflies are everywhere on the West Coast of the South Island of New Zealand. There's only one product that works and you have to buy it there. Deet doesn't work. Nothing works except whatever the locals will tell you to buy.

We bought a product in an outdoor shop in Queenstown (somewhere near the airfield - i think!) called Natrapel, it's actually made in the states, but is what the locals recommended. It is deet free and safe enough on the skin that I was happy using it on our baby - and we did need it!