Hi Perch,
If those were my feathers, I would go to the laundry section of the grocery store and buy a box of BORAX. Put the feathers in an Isolation box (Rubbermaid with a tight fitting lid)and dump BORAX on both sides of the feathers. That will take care of any critters amongst the feathers and in the feather quills. Leave it in the closed up box for a couple of months then take them out, wash thoroughly with a good quality pet shampoo or DAWN dish soap. Let them dry thoroughly and then repeat step 1 with fresh BORAX and let it sit for another month and then repeat step 2. There should not be anything left in or on the feathers but I would not take any chances with having any of your other expensive tying materials becoming infested by untreated "gift" feathers. Keep them in the isolation box.