It does depend on whether you want to kill them or not.
But if you dont mind killing them - switch off the drive and use a vacuum cleaner against the fan opening. This will not only get rid of the ants but will clean the drive of dust that could help prolong its life.
Incidently the term of a software fault being called a bug is from the days when a valve based computers occupied whole rooms - if an insect landed on the racks it would often cross contacts causing an error - hence the term debugging.
Last edited by Jofm5; 20th Feb 2009 at 20:07.
Reason: Added bug info