There seems to be a an intellectual reflex that whenever the topic of exponential growth comes up, people have to bring up growth limits and population density.

There seems to be a an intellectual reflex that whenever the topic of exponential growth comes up, people have to bring up growth limits and population density... In this case though, I don't think that resource limits apply that much. Individual ants feed each other, so they can survive quite long periods without food, and they don't grow much beyond carrying capacity. If circumstances change, they can do a "soft landing" by downsizing the colony slowly or even moving the colony. In fact, colony size seems to be most often limited by burning off excess capital in sexual broods. Compared with most other insects, ants are actually much worse at building up biomass. But the queen ant's survival is actually safer because the colony manages risk and growth.