they are bad in all the SMB islands. When Redland Council sprays with helicopters it helps a lot. Keep well clear of areas with mangroves. Actually they are midges not sand flies and the pustule from their bite is very itchy and painful for 7 days or so. You nearly always get at least 2 bites each time.
I read that a metal teaspoon dipped in quite hot water then placed firmly, convex side down on the bite will actually heat the proteins in the toxin and break them down and render the bite painless. Midge bites are purgatory. Does anyone know how the dogs fare over there?