Ants are driven by the environment. Key factors involve the changing environment such as weather. If you notice ants are ascending up a wall, or into your roof, then it’s quite likely that there will be rain coming, as ants are particularly sensitive to barometric pressure, and will seek higher ground if they are predicting rain. They may also simply be heading to a palatable food source, such as food crumbs, or sugar. Some ants will consume decayed timber, so there are many conditions which can affect their behaviour.
Ant treatments can be very effective once the feeding preferences have been determined, however they can ‘seem’ to return after a recent ant treatment, without realizing that once an ant colony has been eradicated, another one may quickly take it’s place.