This is a simple expression that you add to, to track bots.

() = (what to find)

| = or

preg_match_all("/(spider)|(bot)/", strtolower($_SERVER['HTTP_USER_AGENT']), $userMatches, PREG_SET_ORDER);

simple count the $userMatches, if the array has no matches, no BOTS

count($userMatches);

You can then insert into a database with datetime and track what and how offen the BOTS are in your website.