Dig, Dig Faster!

[Riker]

I have recently gotten some harvester ants through the mail, no queen.  Put them in a farm and they dug a small area very fast but then quit, there is still lots of room to dig.  They are still alive but not digging anymore, they just bunch up or wander around.  Wondering if it was a temperature thing I placed them in a warmer area that is around 80F-90F, before it was about 70F.  They started moving faster but still didn't do anymore digging.

Is there anything I can do to get them to dig more?
Thanks

[Wood~Ant]

They lack the incentive to make a large nest because they have no queen. No queen means no eggs to make more workers, so leaving the colony to remain at its current number of ants which will slowly but surely die off with age.
Having an egg laying mother in a colony means that eventually the adult ant population, as well as the brood, will swell in number which means that workers dig more chambers to expand the nest.