Blue and yellow are the predominate colors in these fairly large (6/0 and larger) Scarlet Macaw coverts. As you can see in the picture above they will vary slightly in color scheme from pair to pair but fall into the range depicted. They are (and were) the feathers of choice for the Evangeline wing. A pattern created by Maj John P Traherne, popularized by George M Kelson in the Fishing Gazette and immortalized by Paul Schmookler and Ingrid Sills in their First work The Salmon Flies of Maj John P Traherne published in 1993. Evangeline is the fly in the background picture (page 87 of that book) above. The coverts measure 3 to 4 inches in the colored portion.