And here the Stanford paper performed a long term study on mealworms and a styrofoam diet as opposed to a control. As for why they didn't reference the previous discovery, it could be for a couple of reasons:
1. The primary author(s) were not distinctly aware of the discovery.
2. If nothing was published in the 2009 Intel International Engineering Science Fair, then there is little to reference. Referencing a news article in a journal is not often considered good practice, and in many cases can be considered unacceptable.
This is a case where I would say "do not attribute to malice...", as I don't see any direct benefit to the researchers for excluding this reference in their paper. Their study focuses on long-term results, not merely "mealworms can eat styrofoam, news at eleven."
I would be very surprised that Intel IESF awarded prize to research projects without a paper! Also, from the links referenced above, I clearly saw the high schooler was presenting in a whiteboard with her research paper with diagrams.
Granted, I am unsure if the paper was published in any established academic journals/magazines etc. or gone through any peer reviews. But considering she was a 16-year-old at the time, with only more than a year of research into this subject matter and with a fairly accurate conclusion.
I would be surprised if those award winning high schoolers had no assistance from professors to teach them how to do research and write papers.