Sevin use is fine, but Ivomec is better and safer. Eqvalan is the water soluble version used for horses. 1-3cc gallon for bath water; 1cc to a quart spray bottle. Use a syringe to measure the CCs--available at most feed stores that sell horse supplies (or online supplies). Effective against BOTH lice and mites--spray perches and nest boxes with the spray bottle mixture. Not a danger to squabs or eggs BUT I'd NOT spray them directly. Use the same syringe to treat for worms--2 to 3 drops directly into the mouth of the pigeon. It, too, can be used in the water, 1.5cc to 6cc, for worms. Higher dose is for ascarids or tetrameres. You can use the Ivomec that is NOT water soluble (cattle preparation) for direct application down the throat. These are the recommendations made by the Assn of Pigeon Veterinarians.
Shannon