if they are mites (tiny little orange critters), you can oil your rats. get some olive oil, rub it all over all your rats, then just leave them. they will be oily for a couple of days, but the mites will drown in the oil. oil again a week later, then a week after that. this will ensure that all the eggs have drowned, also any stubborn hatchlings.
olive oil will not hurt your rats. your rats might not be happy with you for a couple of days (i know mine weren't) but in the long run, they will thank you for it.
Mites are too small to see, if you can see reddish or brownish bugs it is lice. Olive oil baths usually work well to relieve symptoms but aren't nearly as good as Ivermectin or Revolution at eliminating the problem.