C.A.
Sarah is correct. This is a symptom of an anxiety disorder and/or obsessive compulsive disorder. I know. I had a similar problem as a child. Get the child assessed by the pediatrician and the psychologist. Medication and/or behavior modification are probably needed. A lot of this type of disorder is hereditary, so if you or his father have family members have similar symptoms of nail biting, hair pulling, compulsive behavior, depression, etc, then you will need to be prepared for this to be a lifelong thing that need not be bothersome. It's kind of like an allergy that can be treated by medication and avoidance of the problem (like cats). My brother and I both still as adults have the occasional relapse of anxiety, but we know how to control it. A child doesn't and that is when parents need to step in. A buzz cut is a short term solution but might be displaced by another, like chewing pencils, nails, pulling out the eyelashes, etc. Get the assessment and then get an action plan. Good luck.