question regarding biter expansion

[tmzasz]

does disabling expansion prevent new spawners from forming at already established bases or just going out and forming new bases? ( tooltip and wiki not 100% clear on this )

[NotRexButCaesar]

Biters won’t “expand” default generation bases to areas you have already cleared.

I don’t believe, even with expansion on, that biters make already existing bases larger.

[JimBarracus]

deactivating biter expansion means, that no new biter nests are created.
They spawn once uppon chunk creation.

Normally a group of biters is sent out from time to time from existing nests.
They find a new spot, some biters sacrifice themselves and create spawners or worms at this new location.
Once this process is done the base does not grow further.