Wirrn The Wirrn or Wirrrn ( pronounced " Wir - rin " ) were a race of human - sized insect s native to the Andromeda Galaxy . Biology . Physical characteristics . The Wirrn were roughly human - sized , though with an anatomy more like an Earth - based insect . Their heads were made of two large golden eyes , long , floppy antennae , and three small mandibles . Underneath the head were larger mandibles which they used to talk . They communicated by squeaking , though Noah was able to speak human languages . The head was attached to a long thorax which had six long arms attached to it . Though thin , these arms were as strong as a human ' s and could be used for similar tasks . Underneath the thorax was a long abdomen . They could recycle carbon dioxide back into oxygen . The Fourth Doctor believed this was almost certainly done using enzymes . Wirrn lived in space for most of their life and thus they could reuse their waste products with special enzymes , allowing them to survive without fresh air for years . They would only occasionally land on planet s to gather air or food or to breed . The Wirrn were a very tough species , able to survive in a wide variety of environments , energy blasts , and apparently diamond - tipped blades . ( PROSE : " Placebo Effect " ) The Wirrn ' s most important weakness was their vulnerability to electricity . ( TV : " The Ark in Space " ) Life cycle . Wirrn had an unusual life - cycle which was shown on the Ark . The Wirrn started breeding with a queen , who searched for a suitable planet . The Wirrn used cattle - like creatures in the Andromeda Galaxy , but they could also substitute human s . When the Wirrn Queen found a suitable host , it laid an egg in the host . The larva gained all the racial memories of the Wirrn , as well as the host ' s knowledge . Eventually , the larva ate the host and escaped . This larva was a large , green , slug - like creature with several small limbs . These larva , while not as tough as an adult , were still resistant to a large amount of damage . If damaged , they could simply shed their skin , revealing an undamaged skin underneath . The larva produced a green slime , which could infect other creatures , turning them into larvae as well . These infected individuals gained all the knowledge of the Wirrn " and " the previous host . Eventually , the larva started to undergo metamorphosis , creating a large pupa . After a few hours , full grown Wirrn came out of the pupae and set out to do the bidding of the swarm . ( TV : " The Ark in Space " ) One of the these adult Wirrn , generally the first one infected , would become a Swarm Leader and control the actions of the other larvae which were infested at the same time . Some would also be turned into Secondary Queens , allowing them to lay eggs in more hosts . ( PROSE : " Placebo Effect " ) History . The Wirrn had a presence in the universe for a long time . A dead Wirrn was found in a prison ship that launched in 2000 BC . ( TV : " The Stones of Blood " ) The Wirrn left the Andromeda Galaxy at some point before the end of the 40th century , looking for new sources of hosts . They eventually made their way to the Mutter ' s Spiral , where they occasionally infested the odd planet . As they gained new hosts , they were able to learn about the political structure , allowing them to plan out an invasion . Eventually , they reached Earth and were able to infest Miles Mason . Using his connections and scientific skills , they were able to produce drug s to be given to the athletes of the Olympics which would infect them . Those who were not infected immediately would then return to their home planets and infect others . The Swarm Queen then moved to Micawber ' s World to better organise the swarm . She converted the people who came to investigate the tunnels of Micawber ' s World , adding to the swarm . As well , Reverend Lukas of the Church of the Way Forward picked up her telepathic communications and believed that she was his God dess . Using the murder of the Duchess of Auckland as a distraction , the drug was then activated . Unfortunately for them , the Space Security Service ( SSS ) was prepared and ready to drive back the larvae . The swarm was eventually stopped when the Eighth Doctor confronted the queen , exposing the wiring of Micawber ' s World and electrocuting her . Despite this , some of the larvae escaped and stole a ship , instinctively escaping back to the Andromeda Galaxy . As well , the body of the queen was taken by Reverend Lukas , who wanted to spread his Goddess ' message throughout the galaxy . ( PROSE : " Placebo Effect " ) Thousands of years later , the humans first reached the Andromeda Galaxy and started to expand there , destroying the Wirrn Breeding Colonies along the way . After thousand years of fighting between the two species , the Wirrn were driven out of their own galaxy and forced to drift into the universe . One queen ended up in Mutter ' s Spiral and discovered the frozen survivors of an irradiated Earth in the Ark . Though the queen was killed by a security device , it was able to implant an egg in one of the humans , Dune . Eventually , the larva escaped and was able to infect Noah . The Wirrn intended to use the sleeping human s as a food source and to gain their advanced knowledge to help take over the " empty " Earth . However , Noah ' s human side reasserted itself and led the Wirrn into the Ark ' s transport ship , even though he knew it was rigged to explode . ( TV : " The Ark in Space " ) Human colonists in Wirrn space began sacrificing one of their number to have Wirrn queens gestated inside them ; due to the influence of human minds on the queens , peace was achieved between the two species . Following the expansion of GalSec and their takeover of these existing colonies , however , the sacrifices were ended . As a result , a huge and vicious war erupted between human and the Wirrn , lasting generations . ( AUDIO : " Wirrn Dawn " ) Undated events . A Wirrn attended Bonjaxx ' s birthday party at Maruthea . ( COMIC : " Party Animals " )