Hello, I have a small flock of a few pigeons and two babies just getting the last of their feathers. For quite some time now i have had a problem with parasites on the feathers of my birds. They are about a centimeter or less long and are kind of yellow/grain colored. They are long and thin. I have dusted the whole flock with food grade diatamacious earth sevral times. after that there are less of them for a while, but they never totaly go away. they look like they itch, and enough is enough. Any info on what these are and how i can free my birds of them would be awesome. thanks so much!