To help me understand your question, please tell me:
* What did you mean by "gebels"?
* Where did you hear this word?
* What kind of creature did you have in mind?
Once I have more information, I can try to answer your question.
Why do gebils bite?
It seems like you're asking about "gebels," but that's not a recognized term in any language or context. It's possible you meant a different word, or perhaps you're thinking of a fictional creature.