I would use Alphaghetti's suggestion. Personally, I wouldn't leap to reporting them to CAS unless there are other things going on that make you feel the child is being neglected. I know some people alternate bath nights because of dry skin/exzema type problems, but I would expect them to at least wash hands, faces and feet and personally, I feel a child in diapers should be bathed daily to clean the diaper area properly as well. Definitely try to mention it in a non-confrontational way or send out a memo about how dirty they get playing outside in the summer and how a nightly bath is really necessary to keep the daycare area clean.