Ants will find any edible grain that's loose in your house, so if any morsel of food has ever toppled out of an open bag when put back on the shelf, there may be a bug problem in your cupboard. Instead of trying to scrape up every last crumb, do what Grandma would've done to vanquish a bug problem.
It's a simple solution of placing a few bay leaves in your cupboard to help discourage ants and other creepy crawlies from settling in. This will also give your cabinets a nice, herbal aroma.
The potent smell of cloves also proves an effective deterrent to roaches and ants -- and won't repel you like the smell of chemical repellents. Try laying a tiny trail of whole cloves along baseboards and near doors. Put some in kitchen cabinets and drawers, too, if you find the invaders there.