They are flour beetles. My wife had this bag of all bran flour we used once, they had taken over the box. All flour comes with beetle larva in it, just we cook it out. If you don't use the flour for a long time, and keep it in a warm place, the beetles will hatch. They are about 2mm long and are dark brown/black in color as adults.
http://en.wikipedia.org/wiki/Flour_beetle
We are putting down that home defense stuff, but mostly he said just clean up their food source.