From : The Andromeda Galaxy
“We shall absorb the humans!The Earth is … OURS!” Swarm Leader – Ark In Space
Alien – before Alien!
The Wirrn Swarm, were an intelligent large ant-like insect race; which came from the Andromeda galaxy and used other organisms – as food and egg-hosts.
They could recycle their bodily wastes and could sustain themselves, for years living – in the vacuum of space. Occasionally, they would land on worlds, to scavenge for food; or to breed.
They begin life as a huge slimey green maggot, having been implanted into a host’s body; which upon hatching becomes a food source.
The maggots possessed a clever defense (and survival) mechanism; which meant that a touch from the maggot would cause the unfortunate victim to change at a cellular level into an adult Wirrin. Every consumed (or changed) human’s knowledge would be retained and added to the Wirrin collective conciousness. The maggot would then pupate, before the final insect stage.
A Wirrn queen managed to infiltrate the Ark but was mortally-wounded, by the automatic sentry weapon. With it’s last vestige of strength, it impregnated a comatosed human in hypersleep; before dying in a broom cupboard.
This unfortunate consumed individual, was an engineer aboard the Ark. This gave the Wirrn, detailed knowledge of the spacestation and its workings.
A recently-hatched maggot, touched the leader of the Ark; Noah, (who was woken from hypersleep by the Doctor). This left a slimey green residue, on his hand. Over time, the residue spread up his arm, like an infection. Until his body morphed, into the maggot stage of the Wirrn.
The Doctor used electricity, to electrify the spacestation and drove the rest of the swarm; into space. When Noah, in his new Wirrn adult-phase was persuaded by the doctor to board the Ark’s lifeboat shuttle and leave. Noah agreed, as his human-conciousness hadn’t yet been fully assimilated.
Noah’s last act, was to blow the shuttle up; his human side finally overcoming his Wirrn survival instinct, just long enough – to save the remaining sleeping humans, on the Ark.
On a seperate adventure, the Fourth Doctor found a single dead Wirrn, inside a Megaran space-station prison cell; in The Stones Of Blood – 1978.
The Wirrn Swarm still scavenge the far reaches of space but did not make a follow-up appearance in Classic Doctor Who.
Season Eleven – 1975
The Ark In Space⭐⭐⭐⭐⭐
Season Sixteen – 1978
The Stones Of Blood (cameo)🔵🔵🔵🔵⚪