Q: I have a ficus tree in my office that is doing very well. When I watered it I noticed a gazillion ants in the dirt. Will this hurt the ficus?

A: The ants may be finding aphids or mealybugs in the ficus and “farming” them for their sweet honeydew. Or they may find the soil a handy staging area for their forays into your co-workers’ desks where snacks are kept. In either case, I think you should get one of the gel ant baits (Combat, Maxforce, etc) and put a few dabs around the ficus’ pot rim. Ants will eat the bait and die. Examine the ficus for sucking insects and eliminate them too.
See http://pubs.caes.uga.edu/caespubs/pubcd/B1318/B1318.htm