A recent residential case had us researching this! We did not write it, but found it informative…
Five Reasons Ghosts Bite
ATTENTION – a Ghosts of any age sometimes bite to get attention. When real ghosts are in situations where they are not receiving enough positive attention and daily interaction, they often find a way to make others sit up and take notice. Being ignored is not fun. Biting is a quick way to become the center of attention – even if it is negative attention.
IMITATION – Many ghosts do love to imitate others. Watching others and trying to let them know they are around they show their presence to a haunted location. Sometimes as we all do ghosts see others bite and decide to try it out themselves to see if they can affect the living.
TERRITORY – Some believe that real ghosts are trying so hard to show possession of a location. “Mine” and “Me do it” are words that come to mind. Learning to do things independently, making choices, and needing control over a situation are part of a haunting. Biting is a powerful way to control others. If you think about it, it is a quick way to get what you want.
FRUSTRATION – You have to realize that a ghost as being what it is experience a lot of frustration. Being Dead is a real struggle. Consider this when they can’t find a way to make people hear their words to express their feelings, they resort to hitting, pushing, or biting.
STRESS – A real ghost’s world can be stressful, too. A lack of daily routine, interesting things to do, or interaction with loved ones or just another human being are stressful situations for the dead. When a person transits to the other side they also experience stressful events of what they see family members going through. Biting is one way to express feelings and relieve tension. It is also a way to show persons that you do not like what they are doing.
Website source: http://www.hauntedamericatours.com/ghosts/BitingGhosts.php
Author: By Lisa Lee Harp Waugh
Cal-Para Paranormal Research Organization 
How can ghosts bite if they have no body or teeth? I got bit on the back of my leg at my mom’s house. My dad died and she didn’t want to be alone. Me and my two daughters age 11 and 13 spent the night and slept with her on her king size bed. I woke up to my 13 yr old crying,” leave me alone”. She told me little kids were running their hands up and down her legs under the covers and wouldn’t stop. My mom had told me a few years ago she had ghosts of two little girls that were in her house. She’d never seen them, but their voices sounded like baby giggles not over four years old. I told my daughter to pull her legs up to me, and I layed my legs over hers, spooning so they wouldn’t touch her legs. I spoke out loud and told them,” Girls, your mommy is not here, so I’m in charge, I’m the boss. You need to go to sleep Now. No more playing. Time for sleep. Don’t make me mad. ” The next morning, my leg hurt bad. Like I got a cramp at night and it was sore. I told my daughter to look at it and she screamed and said,”Mom, you got bit! I see a big bite mark on your leg and it’s all purple and red bruised all around it. You can see TEETH!! 8 on top and 8 on bottom, but they are LITTLE, like baby teeth. And they are deep” I know I provoked them, but I didn’t know they would turn violent. I feel it was Demons, and not children that bit me.
My mom has passed, and that house gone, demolished by the people who bought it to build a parking lot. But I will never forget that morning I woke up to find I had been attacked by a paranormal entity. This happened in Houston,Texas in Oct of 2005.
What a story! Thanks for sharing; it helps us to be aware. The ‘D’ word is thrown around too loosely; there are ‘lower level energies’, which are negative and considered bad news LONG before there are demons.
However, this is a good example of why we advise to not trust ‘children voices’; often used to fool people.
March 29 2017 I woke up with a bite mark on my arm an were I am bit at on my arm I can bite my self it hurts an it is burse
Are you saying that you bit yourself?