50,000 dollars of the movie's budget went towards spiders. The producers offered to pay ten dollars each for live tarantulas, and handlers collected 5,000 of them.
Tiffany Bolling was cast in the female lead role because she was the only actress who auditioned who had no trouble working with spiders.
The film crew painted thousands of fake spiders on buildings along the main business district in Camp Verde, AZ, to give the impression of a large swarm of spiders. After the production wrapped they hastily repainted the town without much attention to detail. For several years afterwards the stenciled tarantulas were still easily visible on the lighter colored buildings in Camp Verde, hidden only by a thin coat of cheap cover-up paint.
Donna Mills auditioned for the female lead, but couldn't do it because she was uncomfortable with spiders.
A sequel was planned to be released by 21st Century Film Corporation in the late 1980s/early 1990s but was never made. William Shatner was attached to return and was also set to direct.
The large amount of tarantulas kept on-hand led to some unusual production difficulties. Not only did each spider have to be kept warm, but because of the creatures' cannibalistic tendencies, all 5,000 spiders had to be kept in separate containers. Additionally, tarantulas are usually shy around people, so fans and air tubes often had to be used to get the spiders to move toward their "victims". Indeed, in a number of the scenes where the tarantulas are "attacking" people, it is obvious to the viewer that the spiders are merely moving around, usually away from their intended victims.
Bettie Bolling--who played Mildred, the telephone operator--was Tiffany Bolling's mother.
William Shatner initially did not want to do the film, but John 'Bud' Cardos personally visited Shatner at his house, and convinced him to take the role.
Contrary to popular belief (and in the film), the venom of most tarantulas is not dangerous to humans, causing no more harm than a bee sting (unless the person is allergic to the venom). The worst injury most of the actors suffered while handling the tarantulas was troublesome itching caused by the spiders shedding their urticating bristles.
In a nod to the movie's low budget, in the scene where the Baron crashes his cropduster into Earl's garage, the people outside of the station when it happens are not stuntmen. Rather, they are stars William Shatner, Tiffany Bolling, Hoke Howell, and some extras.
The bulk of the score was film library music, which was largely made up of music cues by Jerry Goldsmith from various episodes of The Twilight Zone (1959).
Final film of Roy Engel.
Though Altovise Davis (wife of Sammy Davis, Jr.) is listed as "and Introducing," this was actually her third movie--she played a deputy in Welcome to Arrow Beach (1974), and a co-worker of Gladys Knight in Pipe Dreams (1976).
Jon-Jon, who plays the injured boy covered with spiders during the tarantulas' assault on Camp Verde, is the son of director John 'Bud' Cardos.
Bo Svenson was offered the lead role, but turned it down.
Riffed by the guys from MST3K under the Rifftrax name, Michael J Nelson, Bill Corbett and Kevin Murphy.
William Shatner's face would become the iconic mask for Michael Myers, a year later.