Bug is a 1975 American horror film directed by Jeannot Szwarc and written by William Castle and Thomas Page, from Page's novel The Hephaestus Plague (1973). Shot in Panavision, it was the last film Castle was involved in before his death in 1977.^[1] The film starred Bradford Dillman, Joanna Miles and Richard Gilliland.

The film initially depicts a new insect species, which faces extinction. A widowed scientist crossbreeds the species with cockroaches, creating a sentient hybrid species of insects.

An earthquake releases a species of previously unknown insect which can create fires by rubbing their legs together. Eventually however, most of the bugs die because they cannot survive in the low air pressure on the Earth's surface.

After the wife of a scientist dies when one of the insects crawls in her hair, Professor James Parmiter keeps one alive in a pressure chamber. He becomes obsessed with the insect and successfully breeds the new species with a modern cockroach, creating a breed of intelligent, flying super-cockroaches.^[2]

Parmiter goes into seclusion at a farm after seeing his creation and gaining the ability to communicate with the bugs.^[3]

• Bradford Dillman as Professor James Parmiter
• Joanna Miles as Carrie Parmiter
• Richard Gilliland as Gerald Metbaum
• Jamie Smith-Jackson as Norma Tacker
• Alan Fudge as Professor Mark Ross
• Jesse Vint as Tom Tacker
• Patty McCormack as Sylvia Ross
• Brendan Dillon as Charlie
• Frederic Downs as Henry Tacker
• James Greene as Reverend Kern
• Jim Poyner as Kenny Tacker

It was writer and producer William Castle's last film before his death two years later.^[4]

On the review aggregator website Rotten Tomatoes, 33% of 12 critics' reviews are positive, with an average rating of 4.3/10. However, the sci-fi review site Moria was kinder to the movie, calling it Szwarc's best film. It noted that the movie was better than expected, and the first part of the movie at least maintains scientific credibility. They also praised the lead actor's performance.

Variety found the film static and lacking interest. TV Guide liked the music and found the technical credits good, but overall found the movie mediocre.^[5]

Entertainment Weekly gave the film a C,^[6] while Leonard Maltin gave the movie two stars. ^[7]

The New York Times found the movie "sickening" and felt it deserved a harsher rating than PG.^[8]

The film made just over eight million dollars worldwide.^[9]

• List of American films of 1975