The small spiders used in the film were Avondale spiders (Delena Cancerides), a harmless species from New Zealand that were provided by Landcare Research in Auckland. Despite their fierce appearance, this spider is docile member of the crab-spider family and are, in fact, harmless to humans. They were not allowed back in New Zealand for quarantine reasons. The giant "spider" used in the film was a species of a bird-eating tarantula, which attains an 8" legspan or more. Those types of tarantula are not easy to handle and can give a nasty bite. The spiders in the film were managed and handled by famed entomologist Steven R. Kutcher.
Canaima is the name of the avenging spirit of the Guyana Indians. It's also the name the area in Venezuela where the beginning of the movie was filmed and home to the world's tallest waterfall, Angel Falls.
The species in the film are Eusocial with a hierarchy reminiscent of ants and bees, in reality there is no species of spider that is purely Eusocial, most spiders are solitary with only a handful of species living in groups.
The safety of the spiders was paramount throughout the entire production, so for one scene where McLintock (John Goodman) had to spray an arachnid with insecticide, then squash it with his boot, the production went to extreme measures: first, a dummy spider was sprayed. then Goodman donned special boots with a hollowed out sole for the squash shot, so that the spider would just curl up inside and wait for the next take.
The production required two species of spider: the first - the arachnid that hitches a ride from South America to California - needed to measure about one foot across. The filmmakers found their star in a bird-eating tarantula native to the Amazon; there was only one such spider in the United States. Frank Marshall named the spider 'Big Bob' after director Robert Zemeckis; the production team painted purple stripes on the back of 'Big Bob' and added a prosthetic abdomen "to give him greater bulk".
Though Jeff Daniels claimed that he was fine with small spiders, he acknowledged that "anyone in his right mind" would have issues with spiders as huge as Big Bob. But John Goodman wasn't fazed. "I don't have any problem," he said. "We see each other eye to eye-well, two eyes to their 16-but we get along swell."
When Jeff Daniels came on board to play Dr. Ross Jennings, "Arachnophobia" was a serious horror movie, one that Daniels told Philadelphia's Daily News was pretty formulaic. "You could tell that the lines were kind of written by computer," he said. He and Frank Marshall were hoping for a more ironic tone, so the script went through several revisions, and the filmmakers studied Hitchcock films and Jaws (1975) to get the tone right. One key change: Daniels's character was given a fear of spiders.
While there really are species of spiders that live in colonies, none of these are male-dominated colonies, nor do they have a singular "queen" like ants or bees. Another point in this favor is that the reason common arachnids and other creatures that use an exoskeleton are not the size of houses is that they would collapse under their own weight. The scene at the beginning where the scientists use a numbing agent to collect specimans, would have resulted in quite a few spider bodies that were missing legs. Dropping a tarantula a distance of more than two feet causes it to shatter. These spiders fell from a tree easily one hundred feet tall. In short, none would have lived. Also, insects and other bugs breathe through their skin. Only in the distant past was there sufficient oxygen for giant insects to exist. The General is only about the size of a goliath bird eater, one of the largest known Taratunla species, only beat by the huntsman in leg span, look up pictures.
The trivia items below may give away important plot points.
Frank Marshall saved the shooting of Arachnophobia's climactic fight between Jennings (Jeff Daniels) and the General until the very end of production, after all the other actors have been sent home. The scene, which involved fire, explosions, and many smashed bottles of fine wine, took two weeks of 13-hour days to shoot. Daniels spent two of those days pinned under a 250-pound wine rack, hurling bottles of wine at Big Bob while under strict instructions to not hit the spider - and, in fact, always misses it by three feet or more.
Sheriff Parsons leaves the Jennings' barn to drive back to the mortuary and is not seen again. Stuart Pankin stated in an interview that his character was killed by a spider while driving and crashed his cruiser. The scene was filmed but didn't make it into the final cut of the film.
In the film the species of spider are Eusocial (Division of labour, division of reproductive labour, overlapping adult generations and cooperative brood care) but in reality most species of spider are solitary and aggressive to other spiders. The social species just live communally and don't show all the traits of Eusociality.
In the movie, Big Bob arrives in California and promptly mates with a house spider, creating super deadly offspring. To find the right arachnids for the job, Marshall and his team evaluated a number of species-including wolf spiders, tarantulas, and huntsman spiders-by putting them through a "spider Olympics," running each species through 10 tests, including speed (the faster the spider, the scarier it is), climbing ability, and reaction to heat and cold. The "gold medalist," according to Frank Marshall, was the three-inch-wide Delena spider, a harmless but sinister-looking huntsman native to Australia that was introduced to New Zealand in the 1920s. Marshall joked that "we got them all little passports," which was sort of true: the production did have to jump through hoops to bring 300 of the spiders to the U.S. for filming (and that was just the initial shipment; supplies were replenished every two weeks).
When Professor Atherton (Julian Sands) asks where the photograph of the spider's web hanging in Doctor Jennings waiting room was taken, Sheriff Parsons (Stuart Pankin) tells him it's "the old Daniels' place" that Doctor Jennings bought. Doctor Jennings was played by Jeff Daniels.