Place of origin:
The Foe from the Future
Pantophagen were powerful insectoids, capable of ripping through the metal cities of humanity in 4000, and devoured everything in sight. Despite Jalnik’s hypothesis that the Pantophagen were sentient and talking to him, the Fourth Doctor quickly dismissed such a notion of them being sentient, as he would have been able to communicate with them if they were. (The Foe from the Future)
Little is known about the Pantophagen, before or after Jalnik discovered them during his primitive attempts of travelling through the Time Vortex. Believing they could be controlled, Jalnik and his conspirators attempted to set loose Pantophagen on Earth, but the task of bringing one back turned Jalnik into the first Pantophagen hybrid, ravaged by hunger and capable of devouring a human in moments.
When several were sucked into 1980s Earth, the Doctor used Jalnik’s machine to control ghosts, to age them to death. Afterwards, he sealed the crack Jalnik was using to make his way to earth, preventing the Pantophagen from ever coming to Earth in the first place. (The Foe from the Future)