Although each area can differ, since early May, I have seen and been bitten by, midges in shade sun and stinking hot heat.
Arisaig and the sands of Morar are midge free, few trees and just machair behind the coast.
But other areas can be unbelievable. Try sleeping out in Glen Etive or Skye in a windless day or night.
As others have said a bug jacket, Green Welly Stop Tyndrum has them for £12, is the answer. I think Silvergirl posted a pic of a gazebo with netting.
As a minimum if I'm walking or canoeing I have a flip up headnet that fits over my cotton boonie hat, so it's off my face.
Nick