Here's why:
* "Devour words wherever I find them": Bookworms literally eat through books, consuming the words printed on the pages.
* "But still am no wiser": Despite consuming vast amounts of words, bookworms don't gain any actual knowledge or understanding.
* "Keep your books under lock and key or they will be eaten by me": This highlights the destructive nature of bookworms.
Let me know if you'd like to try another riddle!