Dear Kele, It is possible that the ants are nesting outside your room and getting in through the window sill. It is recommended that all the holes and cracks in the window sill should be sealed to prevent the ants entering your room. Applying any type of powder will deter ants from moving around the window sill area. If this does not work, application of an ant bait in this area will take care of this infestation. Ant baits are available from local supermarkets and garden/nursery shops. Good luck.