Ants are normally in an area for a reason, more commonly food. For the most part ants shouldn't be too interested in hay or pellets (there should be nothing sweet in there) but make sure the pellets are properly sealed anyway. Make sure you keep the cage clean as well, feed the chin just a day's worth of pellets at a time so their isn't pellets sitting in the bowl for long. Also I would look to make sure there is no human food laying around the room, like if you eat in the room make sure you clean up any crumbs.