Can't see any other mention of this in other threads.

IN VoV at around 30.10 seconds, the mother 'vampire' is talking to the Dr about why they came to Earth.

She uses the phrase.

I wonder what 'others' have built a new society on Earth...

I had kind of wondered that myself...

its late here in the USA, the only one I could think of were the bee's! lol

I wondered about that too, but then later she refered (on one or possibly more occasions) to Venice as being their 'new world', rather than Earth, so perhaps she was just refering to those groups of people who have started new societies in Venice (as referenced earlier in the show).