Middle English drane, drone, "male honeybee," from Old English dran, dræn, from Proto-Germanic *dran- (source also of Middle Dutch drane; Old High German treno; German Drohne, which is from Middle Low German drone), probably imitative (compare Lithuanian tranni, Greek thronax "a drone"). Given a figurative sense of "idler, lazy worker" (male bees make no honey) 1520s. Meaning "pilotless aircraft directed by remote control" is from 1946.
Drones, as the radio-controlled craft are called, have many potentialities, civilian and military. Some day huge mother ships may guide fleets of long-distance, cargo-carrying airplanes across continents and oceans. Long-range drones armed with atomic bombs could be flown by accompanying mother ships to their targets and in for perfect hits. ["Popular Science," November, 1946]
Meaning "a deep, continuous humming sound" is from c. 1500, apparently an independent imitative formation (compare threnody). Meaning "bass pipe of a bagpipe" is from 1590s.