An earthquake releases a bunch of mutant cockroaches that can create fire by rubbing their cerci together. Eventually most of the bugs die because they cannot survive in the low air pressure on the Earth's surface, but a scientist, Professor James Parmiter, keeps one alive in a pressure chamber. He successfully breeds the mutant cockroach with a modern cockroach, creating a breed of intelligent, flying super-cockroaches. It is based on Thomas Page's 1973 novel The Hephaestus Plague.

References:
https://en.wikipedia.org/wiki/Bug_(1975_film)