It took me several weeks before my mosquito-bites from French Polynesia were cured, but here in New Zealand, I got attacked several times by sandflies. And they are much more irritating than the mosquito bites.
Most of the time, I was attacked on the most idyllic beaches. Several times, at the end of walks in coastal areas, I rested on some nice, white beaches, putting shorts and t-shirt on, and taking off shoes and socks. To realise after a while, that I am covered in little black flies, which really enjoyed sucking the blood out of my arms, hands, legs and feet. Ever been bitten on the inside of your hands? I can assure you, it drives you crazy when you start to scratch it. So, I learned the hard way: the nice looking beaches are not to sit on: they are just to look at, and property of the sandflies (especially if they are called “sandfly bay” or “sandfly beach”).
Also, in Milford Sound, you see clouds of these little bloodsuckers.
But still, it will not stop me from walking around (but I don’t take off my socks and shoes anymore).