Actually my vermin have not teleported at all, I dug a pit with three cave spiders in cages in it. The doors were locked and the cages opened by an external lever.
In less than a year the cave spiders had filled every single square of the pit and moreover had managed to scale the walls and fill the chamber above it as well.
Once I unlocked the doors for harvesting the cave spiders did disappear though.
I would suggest hollowing out a big cavern, sticking the spiders in it and just lock them in for a while- its not hard to catch new ones to replace them come harvest time anyway, just don't forget that the little buggers can climb walls!