Cybermite

Cybermites are cybernetic insects, controlled and made by the Cybermen. According to the Doctor they were a heavily upgraded form of Cybermat. Even one could partially convert people, (TV: Nightmare in Silver) but to have a full upgrade would take a very large swarm. Because of this, they usually travel in small swarms, and go directly for the victim's head. They are not used in the upgrade process for a full cyber-conversion.