The only way you could patent a fly pattern is if you came up with a new material, or method of making one, and the patent would only cover the material, or method, not the pattern itself.
A fly pattern is the same as a recipe. They are not copywritable. Niether are formulas or other 'lists' because the ingredients are already invented.
And even if you could devise a new method, such as Polaris has, the patent is only for a specific period of time, usually 20 years. It is so the patent holder can try to recover the development expenses through temporary exclusive marketing. And of course, the government can waive a patent if it wants to use the product, such as in the devolpment of nuclear weapons. They are immune from lawsuits.
This was a problem between Colt and Smith and Wesson in the latter 19th century. That's why cartridge revolvers were not manufactured in quantity until after Colt's, Remington's, and Smiths patents ran out in the 1870s. The designs were perfected in the 1860s, but Colt had the patent on the major engineering, Remington had the solid frame patent, and Smith had the bored-through-cylinder and fixed ammunition patents, and none of them would work together. This was probably a good thing. Otherwise the War For Southern Independence would've been even worse than it was, with the use of machine guns (invented in the 1850s by John Browning), hand grenades (invented in 1851), repeating firearms (invented in the 1850s), and land-mines (invented in the 1850s). For once, government short-sightedness was a blessing.
So, all this is just to illustrate why you can't realistically copywrite a fly pattern. But, you can post it here, and I'm sure we will all make sure the credit goes where it belongs. And, you'd be a shoe-in for Fly Of The Week. Personally, I consider the kudos of my fellow Tyers a much greater honor than being assigned a number, to sit in some dusty file cabinet in Washington until someone wants to use it against me.