Those awful things look like eggs to me. It is very possible that you can´t see any critters, because you may have already eliminated the population of lice or mites and that you just have empty eggshells left. Mites and lice both lay eggs but don´t make coccoons. They don´t metamorphose, just get bigger and shed their exoskeletons with each molt. They can cement the eggs to the hair shaft with a very effective protein "glue," hence the difficulty in just pulling the eggs off. If you can look at one of those things under a microscope under fairly low power, you should be able to tell for sure that those are eggshells and not static lice, since you will be able to find legs on those static lice.