According to David Herpin
This drink is widely believed to have been created at Tujague's Restaurant in the French Quarter. Tujague's is the second oldest restaurant in New Orleans and was in operation at the time of this drinks creation. Here is an early printing of this drink:
Dairy engineering: Volume 73 in 1956
"Publicity Council to open Britain's second Dairy Cookery Week, run in conjunction with the June Dairy Month. The spectators were first introduced to an American concoction called a " Grasshopper Cocktail "."
This drink exploded into mainstream american drinking culture in the late 1950's, large in part to Hiram Walker's marketing campaign as seen here:
LIFE - Feb 17, 1958 - Page 137 Vol. 44, No. 7
"Hiram Walker's CORDIALS A Rainbow of Distinctive Flavors GRASSHOPPER 1 oz. Hiram Walker white Creme de Cacao • 1 oz. Hiram Walker green Creme de Menthe • 1 oz. light cream • Shake with ice and then strain into chilled cocktail glass"
LIFE - Oct 26, 1959 - Page 16 Vol. 47, No. 17
"Grasshopper 1 oz. Hiram Walker White Creme de Cacao. 1 oz. Hiram Walker Green Creme de Menthe. 1 oz. Light Cream. Shake with ice and strain into chilled cocktail glass."
However Hiram Walker may not have created this drink, only capitalized on it. Here is an early story on the proprietor of the drink:
Cue: the weekly magazine of New York life in 1955
"you might try a Blue Blazes for a kick, a new drink concocted by Sidney Allen, who started the Grasshopper craze."
This drink dates between 1951 - 1953 and contained at least as of then:
Shake these ingredients:
Light Creme de cacao
Green Creme de Menthe
Strain into a chilled cocktail glass.
"Daily Herald", Chicago, Illinois, 5th February 1953
- 1/3—White Creme De Cacao
- 1/3—Green Creme De Menthe
Shake with cracked ice Strain into cocktail Glass