Do I need to be on my parents car insurance policy to drive it for a day?

I am over 18, and my parents live in my home. I do have a license, but don't own a car as I take public transportation. Do I need to have auto insurance to drive his car for a few days? As in do I need to be put on the policy for just a day or two or is it alright? Assuming I don't get into any accidents or get any violations?