The squeaky wheel gets the grease. Put in a maintenance request EVERY DAY you still see ants and put in picture proof with your request. It's likely that the maintenance department has to report every month to the board on "number of requests submitted" and "number of requests completed." There needs to be a paper trail for your requests.

You absolutely should not be spraying any ant killer in your room. There are people in the district that are required to be certified to spray for pests, or at least have to hire an outside company that is certified. You are opening yourself up to a liability issue if you spray something that a student negatively reacts to in your room.