ARGUS drone
From Halopedia, the Halo wiki
ARGUS Drones are small, one meter wide aerial Drones equipped with ARGUS detection systems, targeting computers and a single Lancet Micro-missile with shrouded rotors. Their function was to detect explosives on motorways and in buildings.
They are likely named after the Argus Panoptes of Greek Mythology, a giant with a hundred eyes and servant of Hera. It killed the bull that ravaged Arcadia, which is also the name of a UNSC colony world, Arcadia.