lily-leaf beetlePlease read the article in this link, written by Crystal Ernst.  Crystal is, in my opinion a leading researcher (and Canadian too!) on this pest.  She has been the guest speaker at a few seminars to lily society members in North America and provided some useful insight into the habits of the lily leaf beetle.

pdf file The Lily Leaf BeetleThe Lily Leaf Beetle: An Unwelcome Invader by Crystal Ernst, B. Sc., M. Sc.