The final film produced by B-movie kingpin William Castle, Bug starts out like a standard-issue monster movie, then morphs into a tragic character study about a mad scientist. Later, Bug enters quasi-surrealistic terrain thanks to inexplicable character motivations, jarring lapses in story logic, and a gonzo finale peppered with apocalyptic overtones. Very little of what happens in Bug makes sense, but the film is strangely beguiling nonetheless. Bug opens with an impressive earthquake sequence that’s staged entirely inside a small church. Next, director Jeannot Szwarc’s probing camera reveals that giant, mutated cockroaches have invaded the small California town in which the church is situated. Meanwhile, the story zeroes in on Prof. James Parmiter (Bradford Dillman), a science teacher at the local college. Thanks to clues provided by townie Gerald Metbaum (Richard Gilliand), who witnessed strange phenomena in the desert, Parmiter determines that the cockroaches emerged from deep inside the earth after the quake. Evolved for survival under massive pressure, the bugs have the ability to spark fires. Yet Parmiter’s realization comes too late to prevent tragedies including the death of his own wife (Joanna Miles), so Parmiter seeks revenge against the killer insects.
That’s when Bug drifts into craziness. Parmiter captures a specimen, holes up in a remote cabin, and performs experiments including crossbreeding the “firebugs” with common cockroaches. A diving bell is involved. Concurrently, characters wander around town as if nothing unusual is happening, even though citizens are dying from spontaneous combustion at a rapid clip. On one level, Bug is so outrageously stupid that it’s almost a comedy. On another level, the movie is fleetingly effective as a horror show, thanks to elaborate scenes of bugs crawling onto people and then bursting into flames. On a third level, Bug is fascinating simply because the storyline is constructed in such an eccentric way—for the last 45 minutes of the movie, nearly all the screen time is devoted to scenes of Parmiter hanging out with bugs in his makeshift lab. Dillman’s twitchy performance is fun to watch, even though his characterization is cartoonish and silly, and director Szwarc—who later returned to the shock-cinema genre with Jaws 2 (1978)—shoots the material for maximum pulpy impact. Not a single frame of Bug can be taken seriously, but insufficient credibility has never been on obstacle for enjoying creature features.