ankle-biter 
noun humorous, chiefly North American & Australian /NZ
A child: travelling overseas with an ankle-biter has its advantages...
- You can keep the ankle-biters satisfied with a kids' menu made up of perennial favourites such as chicken nuggets, fish fingers and sausages.
- Even though three in four of these women are grandmothers, many of them must still be alert to ankle-biters around the house: 11 percent of this group live with children (either their own or someone else's).
- I figured you'd look like an ankle-biter like the rest of your form.