Mosquito

Mosquitoes were non-sentient insects native to Earth. They were known for plaguing campers while they slept. (PROSE: Cat's Cradle: Witch Mark)

Biology
The Fifth Doctor claimed that the London Underground had its own unique species of mosquito. (PROSE: Light at the End of the Tunnel)

Earth
In 3rd century Germany, robotic mosquitoes were spreading disease and killing off dozens of soldiers. They were being used by aliens to search for a cure to a plague infecting their own world. (PROSE: Silver Mosquitoes)

In October 1947, Robert Chate visited Maria Coleman's house in the San Fernando Valley in California and observed mosquitoes in the overgrown garden. (PROSE: Dying in the Sun)

In 1982, The First Doctor and Steven Taylor killed a giant mosquito on Earth which had been swollen to its enormous size by some alien substance. In Reading its remains combined with snow and the DNA of two human boys, causing the two snowmen they had made with their mother to come to life. They were rescued from being melted by the sun by the Fifth Doctor, who took them to the North Pole. (PROSE: Do You Smell Carrots?)

Jason Clearfield experimented with creating giant insects as hosts for the minds of Wyrresters. The mosquitoes he made had scopolamine in their proboscis to control the local villagers. (PROSE: The Crawling Terror)

Elsewhere
Atraxi 3 was inhabited by giant mosquitoes. (PROSE: Vampire Science)

Similar species
Terravores looked like mechanical mosquitoes. They had extremely limited vision. (AUDIO: The Crimes of Thomas Brewster, The Screaming Skull)

Other references
Captain Jean-Luc Picard likened the prospect of the USS Enterprise-D engaging a Cyberman Fleet to a mosquito against a herd of elephants. (COMIC: Assimilation²)