"How does it feel to be on the other end of a microscope?"
-Dr. Robert "Rack" Hansen.
For all intents and purposes, the first great 'creature feature' (which didn't involve the creature in question being played by an actor) was King Kong (1933). That film is deservedly part of cinematic lore with FX that are more endearing than Peter Jackson's lame 2005 remake of it. Godzilla (1954) followed and became influential itself thanks to that story's use of atomic power to introduce its monster. Nuclear radiation became a staple of horror throughout the 1950s, such as in the Universal film Monster on the Campus (1958); films which blamed atomic power for nature's creatures running amok on humanity.
Alfred Hitchcock chimed in with his great film The Birds (1963), and Steven Spielberg shot to the top of the A-list with his classic entry in this genre, Jaws (1975). It was the latter which led to a rebirth of nature gone amok films in the 1970s. Like The Birds, many of these films didn't blame nuclear energy for animals declaring war on humanity, the animal antagonists simply decide to do so one day. Grizzly (1976) quickly followed, as did Alligator (1980). One film which offered a scientific explanation was Piranha (1978), in which the vicious fish are explained as being genetically engineered. Stephen King's contribution came with the 1981 publication of his great novel Cujo, which, in turn, became an equally great movie in 1983.
Some of these films blame humanity's actions for nature to turn on them. One such example is Kingdom of the Spiders, which, as the title suggests is about spiders(tarantuals, specifically, but I guess producers thought Kingdom of the Tarantulas wouldn't have been as cool a title) attacking human beings. The reason for this attack, though, is explained as being the use of pesticides which have resulted in the arachnids' natural sources of food dying out, hence, our eight-legged friends have to resort to humanity and livestock for food.
Robert "Rack" Hansen (William Shatner) is a veterinarian in a small Arizona town who begins to suspect trouble after a calf belonging to his friend Walter Colby (Woody Strode) mysteriously dies. Not long after taking his findings to a lab, an arachnologist named Diane Ashley (Tiffany Bolling) contacts Rack and informs him that the calf dies from spider venom. Rack is skeptical at first but welcomes her input, especially after Colby's dog and bull die from similar circumstances. Colby also discovers a massive spider hill in the back of his barn and, with Rack and Ashley's help, burns it down.
However, some of the tarantulas manage to escape and, over the next few days, begin to attack and kill human beings, including Colby. Rack and Ashley attempt to get the mayor (Roy Engel) to stop this manifestation by using rats and birds (the natural enemies of tarantulas) rather than the usual pesticides. However, like the mayor in Jaws, this mayor says that having the town covered in pests won't do because of an impending town festival which is meant to keep the town going throughout the year. Unlike Jaws, though, the mayor here gets what's coming to him during the film's climax.
Eventually, like The Birds, the film ends up with our two leads and a few others barricading themselves inside a building to protect themselves from the onslaught. Another similarity with the Hitchcock film is the ambiguous ending.
One of the biggest reasons this picture has a special place in some hearts is because of Shatner, who does his best to avoid being typecast as Kirk, despite the fact that Star Trek: The Motion Picture (1979) was just two years away. The music by Dorsey Burnett is another plus, weaving (no pun intended) tension throughout the movie, so much so that we can ignore the fact that real-life tarantulas don't do much web-weaving.
Another interesting note is that several of the tarantulas used actually died during production of this film. This makes it doubtful that a potential remake of the film (and I won't be surprised if we see one down the line) could be made with the real things today, as the inferior Arachnophobia (1990) proved.