For one, ant hormones could be used to guide tracks ants to a certain destination. I agree that effects would've been required for a lot of those scenes, just certain ones could've been helped.
As someone really interested in special effects, who has watched many a FX breakdowns, the task of making realistic ants should've been to difficult to accomplish.
I just think the production team wimped out. I mean they used an entire room of living snakes in Raiders, but couldn't pull off a swarm of ants?
I understand that CGI would've been needed no matter what, I'm just saying real ants for parts could've added to the believability of the scene. I too really like the scene, with an homage to the raiders fist fight.
The prairie dogs are still unforgivable. How can you not get a shot of a prairie dog running into a hole? That's all they do.