The phrase 'Bookworm' refers to someone who reads a lot.
Example of use: "She is such a bookworm! She seems to have a new book every day!"
If you love to read books, you may have been called a 'bookworm'. The origin of the idiom “bookworm” probably originated as a somewhat derogatory term for a person who studied or read more than was usual. Bugs such as silverfish, book lice, and linoleum beetles were referred to as bookworms because they inhabited books; thus the idiom.