There was a comment over at Catholic Cuisine regarding the literalness of St. John's diet. Here is what I found after doing a quick Google search:
John was, many believe, influenced by the Essene sect, who ate dried locusts. Some modern people try to refute that the Essenes did, but the Damascus Rule 12.13-14, an Essene manuscript that is part of the Dead Sea Scrolls found at Qumran near the Dead Sea, discusses eating actual locusts.
Modern-day Western apologists, coming from cultures in which consuming insects is next to anathema, write pages defending the theory that Carob beans, not actual locusts, were meant. The actual Greek word, "akris / akrides", though, used here, and in the Gospel according to Mark, means the insect called "locust."
The current thinking among many scholars now  is that John did indeed just plain eat locusts. After all, whatever modern Western feelings are about the matter, the plain truth is that in Judeao-Christian tradition, there is nothing wrong with eating them. In fact, the Bible even states outright that locusts are kosher to eat: "Even these of them ye may eat; the locust after his kind, and the bald locust after his kind, and the beetle after his kind, and the grasshopper after his kind." Leviticus 11:22.
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And also, this Rabbi has answered the question about which locusts/insects are considered kosher to a digestively disturbing degree. Wikipedia also has more about the locust/grasshopper exceptions.
When I come up with a particular treat or menu to celebrate a saint's feast day it's really just my way of finding something interesting and yummy to enjoy with my children as I teach and share with them the most important part of the feast day... the life of heroic virtue that the celebrated saint really lived.
I just want to reiterate that I am no Biblical historian. I leave it in the hands of those much more qualified than myself to determine the truth of what someone ate or didn't eat over 2,000 years ago. That was not the point of our little treat, but it did serve it's purpose of providing an opportunity to discuss the circumstances of St. John's heroic life of virtue, the reason why the Church celebrates his birthday (while not being conceived without Original Sin, it speaks to the long held tradition of the early Church that he was born having been cleansed of it) and also having imaginary conversations with St. John about crunchy vs. honey-coated cricket confections.