Locusts were a race of Earth-native insects. Dodo Chaplet pointed one out to Steven Taylor while onboard the Ark. (TV: The Ark)
The Eleventh Doctor once stopped what he described as a "weapons bearing giant alien locust attack" in ancient Egypt. He met Queen Nefertiti during this adventure. (TV: Dinosaurs on a Spaceship)
In 2009, Ian Webster created the locust virus. This virus could be downloaded to any computer. After the download the computer would rebuild itself as a metal locust. Later the system was advanced, instead of one locust, two locusts were built out of the computer parts. The virus was destroyed by Sarah Jane Smith and her friends. (AUDIO: Deadly Download)