You can't overdose with wormer unless you feed a whole tube! Under-dosing is worse. It makes the worms resistant.Granny I know I give a pea sized amount of ivermectin in the mouth of the chicken but do I spread it where missing feathers are too? Also, if it's not mites or lice will it hurt her if I give it too her.? I really don't know what it is. Will I see lice or mites?