Librarians in Queens do not like to talk about the scofflaws who rack up fines for late books. They prefer to call them “clients” or “patrons” who owe “extended-use fees.” Competing against a tide of video games and cable shows, they are loath to scare away anyone who wants to read.

But their patience has limits. When provoked, they play hardball.

Eleven years ago, the Queens Library system, the largest in the nation by circulation, hired a professional enforcer to collect the 25-cents-a-day late fines as well as missing library materials from books to DVDs to rare musical scores.

The gambit has paid off handsomely. The haul so far: $11.4 million, about half of that in fines. That’s a lot of quarters.

Borrowers who fail to return Queens Library books can be reported to a collection agency and to a credit bureau, with a damaged credit rating as a result  a tactic that so shocked one Far Rockaway rabbi that he filed a lawsuit. The collection policy also has pulled libraries  places where generations of children have learned moral lessons about returning what they borrow  into the debate on just how much punishment is appropriate for failing to return a library book.