stir up a hornets' nest
Make trouble, cause a commotion, as in Asking for an audit of the treasurer's books stirred up a hornets' nest in the association. This metaphoric term, likening hornets to angry humans, dates from the first half of the 1700s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.