The story
Of Mormon + cricket, attested from the late 19th century. Associated with the Mormon settlers due to the miracle of the gulls.
Etymology from Wiktionary, CC BY-SA 4.0.
Mormon cricket
Today it means: A large dark wingless katydid, Anabrus simplex, that resembles a cricket and is found in the arid parts of the western U.S. where it is occasionally an abundant pest of crops. Full definition →