That is almost definitely a bot. The reason it isn't displayed in a different colour is because it isn't on the S/W's list of known bots. If you would like to see who own it enter the IP into
http://whois.domaintools.com/
If you still want to block it, then do as mentioned above and enter those lines into an .htaccess file in the document root of your site. It's not only Apache servers that this will work on, it'll work on Zeus servers too.