Hitty Pitty...

I am  frequently haunted by Squirell Nutkin's rather spooky riddle, especially as represented in a sublime Ros Garbles cartoon. (...What's she up to these days?)
I wish I had a functional scanner... She depicts it as a sinister sausage with a rubber-ring-like , fangy mouth. I often find myself copying it. 
http://www.bugpowder.com/andy/links/sample/garbles.ros.html

WTF is Hitty Pitty, exactly? It's bothering me. (I'm such an obsessive old git, I know it-)

Hitty pitty within the wall
Hitty Pitty without the wall
If you touch Hitty Pitty,
Hitty Pitty will bite you.

UPDATE: 

Finally found it on Google. After all that...The answer is a nettle!  I think I prefer the evil sausage-monster.