When I was reading your concern, it was like reading about my own life!!! I too have a daughter who has been pulling out her hair...and just like yours she twirled it around her thumb and then sucked on it... and also we have two cats, who she would touch and then get it on her hands and put it in her mouth. I will tell you what we did, and it may seem harsh...did to me at first, but I understand why now. I brought the concern to her ped. at her 2 year old check up, and he said that since it was unsure weather or not she was actually swallowing the hair, we would have to buzz her hair... I thought he was joking, but no...he said if she got enough hair in her stomach it would form a hairball, and the only way to get it out was surgery. (A MAJOR SURGERY) so he said if not a buzz, then so short that she can't get her fist around it to pull it. My husband and I thought about this for two weeks, and she kept on pulling, going bald in a spot...so we got her two year pictures taken, and then got her hair cut super short. (we didn't buzz it just yet) she is doing great with it and we haven't seen her pull it since. Better off to do it now before they ruin the hair follicals and have a permanent bald spot, and its also better to do it now before school starts. (piggy tails or not, she is still our cute daughter)