You may be bringing them home from the Grocery store. These pest love to hitch a ride in bird seed, dog food, grits, rice, flour, pasta, cereals,candy bars, and even cork.
We had an infestation probably 8 years ago. I thought the culprit was the sack of stone ground grits that we brought home from the mountains, but after getting rid of the grits and all the moths and larvae... we had them again. It wasn't until I was at the grocery store that I realized that's were the second (and possibly the 1st)invasion came from. The dog food aisle (also were they keep the bird seed) had moths flying around. That's were they had come from. Mind you this is a nice, newer grocery store, so either they came from their warehouse or the manufacturer.
Keep a close eye on everything in your panrty and cabinets. Next time you go to the store pay close attention to the packaging of items you purchase, looking for tiny holes in the packaging and around the folds and flaps for any egg casings or larvae. Store the items in air tight containers (glass or plastic, NO cork tops!).
If all else fails, set off a fogger in the kitchen area leaving all the doors and drawers open. Only thing then you'll have to wash all your dishes and surfaces that food and hands come in contact with.
Good luck!