Bait is the preferred method of control because, in order to solve an ant problem, you need to first eliminate the ants you don't see to get rid of the ants you do see. The workers find the bait, carry it back to the nest, and feed the queen, eliminating her and future populations. 

Ants are a social insect that lives in colonies. Treatment plans should include killing the entire colony. Just spraying an ant with a typical ant spray, particularly a repellent spray will only kill a few at best and scatter the colony. Ants may enter your house foraging for food or seek shelter.