Currently the Tervigons are being kept in check through the efforts of the Dark Angels, disallowing them access to further biomass to increase their numbers.One side effect of this 'containment exercise' recently noted is that their extreme levels of psychic ability has decreased. Whatever obscene catalysing agent that had produced such monstrous powers seems to have been used up. The beasts are still powerful but in no way can they perform the feats of psychic mastery that allowed them to secure a foothold on Ferron soil. Not only that but their spawning behaviour seems to have altered, no longer are they able to spawn with such ferocity, their progeny bursting forth with wild abandon. Instead the alien filth are deposited like mewling newborn infants, weak and decrepit, blinking in the harsh daylight as they try to ascertain why they have been brought into existence. It is advised that anyone facing such an abominable birthing should utilise this moment of confusion to destroy the alien scum.
One bio-magi has suggested that it is Ferron Proxima itself that is fighting back, that it is allergic to the Tyranid presence and thus weakening the bioforms much as the planet is anathema to the Ork threat. Although there was historical evidence that certain have genome sequences that can match up with the Catachan Devil it has since been shown to match more closely with the Ymgarl Mutation but with differences that make the instability of the mutation more harmful to the Tyranid genetic make up than beneficial. It certainly might explain the recent discovery that although the Tervigon as primogenitor spawns the Termagaunts and was able to pass on certain genetic improvements new evidence suggest it no longer imparts any such advantage. In fact the Tervigon is now a mere incubator, or surrogate for some other, unknown brood mother.