If my ALLOWED_HOSTS is set to just .mywebsite.com, will that stop google from crawling my site? Doesn't the the bot have a host of googlebot? Sorry I'm kinda ignorant on this matter..
You should use robots.txt file on webserver to block bots from accessing website. http://www.robotstxt.org/robotstxt.html
Google bot isn't using "googlebot" host, but user-agent. If bot would use "googlebot" as host, then it wouldn't be able to access your website in case if webserver is configured with multiple websites having different hosts.