"  Don't Bite The Hand that feeds You " Even going back to WWI, there has always been legitimate dismay when immigrants and refugees complain about conditions after having been accepted in countries like Canada, Great Britain, the USA and Australia.
This is a reasonably restrained version of the song by Gene Autry. It expresses what many people feel about ingratitude of some newcomers to a better place only to complain.

 https://youtu.be/AJHuX2Xio7A