An eagerly-awaited (and now much-celebrated ;-) update of the author's previous field guide
(1). Currently this is probably the best book resource for overall info on galls of the western U.S., with coverage of diverse gall taxa on a wide range hosts groups, as well as abundant insights into their biology and ecology.
The publisher's web page is
here. A good amount of info, and a taste for the quality of content & presentation, can be gleaned from the "Look Inside" preview accessible through the Amazon web page for the book.