Sweet... you are right it looks a lot like the ant "worm". Altough your pic lacks a bit detail, you can clearly see that the abdomen is segmented and that there are more than 10 segments. This is due because of a secondary segmentation. And there are only 2 families which have such a gestalt and a secondary segmentation: Therevidae and Scenopinidae. And because you found it inside the house (I guess), in a bag of old oats, I think it should be a Scenopinidae or Window fly, which are more often found in houses, while Therevidae are more outside (especially the US ones). I bet there were some Dermestidae or Tenebrionidae larvae in the oats, and this larvae was looking for them... I would even give a guess that it is the cosmopolitan Scenopus fenestralis... but this is just a guess...Great find, I never found the larvae inside the house, only the adults sitting at the window (namesake).