How do I get rid of pantry cast in my flour, rice and pastas?

Thank you for your question. The first step in insect control is insect identification, and, since most of those that infest our foodstuffs are small, "very tiny" may not capture it. However, the following article has photos of the most common pantry insects in your part of the country, as well as control mechanisms: https://agrilifecdn.tamu.edu/citybugstest/files/2016/07/E486.pdf

Hope this is helpful. Good luck!