"Tarantula" was a 1955 movie about a tarantula that grows into a giant after a scientist injects it with an experimental nutrient, according to IMDb.com. The movie was directed by Jack Arnold, screenplay by Robert Fresco, Martin Berkeley et al, and starred John Agar, Mara Corday and Leo G. Carroll.
"Earth vs. the Spider" was released in 1958. The plot involved a giant spider living in a cave. The police spray it with DDT, thinking they killed it. However, it revives and goes on the attack. The movie was directed by Bert I. Gordon, written by László Görög and George Worthing Yates. It starred Ed Kemmer, June Kenney and Eugene Persson.
Monster movies had their heyday in the 1950s and 1960s, reflecting the advances of technology and science, along with some of the fears people had about experiments gone wrong. Young people were especially fascinated by sci-fi horror films.