Ovee 200 grasshoppers were used for the film. During the filming, they began to eat one another. By the time the last shots were done, only a dozen were left.
The National Guardsmen wear the insignia of the U.S. 33rd Infantry Division, which is indeed the designated unit of the Illinois National Guard. The soldiers in Chicago wear the insignia of the U.S. Fifth Army, which at the time was headquartered in Chicago, where the film takes place.
There really is a town called Ludlow, in the right area in Champaign County, IL, and the town Paxton is just north of it in Ford County. They are also near Chanute AFB, where reporter Audrey Aimes (Peggie Castle) was headed at the beginning of the film.
Bert I. Gordon was inspired by Cecil B. DeMille's "The Ten Commandments" (1956), the big movie hit of 1956. That film's biblical plague of locusts became Gordon's plague of giant grasshoppers invading a modern city.
The phone in Audrey's car is a precursor to modern cell phones. It worked off of the Mobile Telephone Service, a VHF service with very limited availability. The user would be connected to an operator, who would then route the call to a second operator that could then route the call to the intended recipient.
Bert I. Gordon actually wrote the story idea for 'Beginning of the End", but Fred Freiberger and Lester Gorn were credited as the screenwriters.
Audrey (Peggie Castle) drives a 1956 Chrysler New Yorker convertible in the movie.
The scene were the giant grasshopper is chasing the running kids, one on bike, are actually relatives of Bert I. Gordon and Flora Gordon. Cousins and neighbor kids of theirs and that's the street they lived on.
Patricia Dean, the one that plays the girl wrapped in a towel, was originally considered for the Audrey part. She also plays the Red Cross Representative in the movie. She is also shown on the films movie poster as the girl laying on the ground screaming in terror while wearing a two piece outfit.
A couple of the scenes of Chicago deserted streets are actually still photos that were taken in the early hours of the day.
Footage of tornado destruction was used as the "aftermath" of the grasshopper attack on Ludlow, Illinois.
Movie was spoofed on MST3k s5 e17.
The sound that Common True Katydids make is used for the giant grasshoppers.