I remember seeing the 1954 film Them! when I was fairly young and wanted to rewatch it to see if it held up over time. I was rather surprised to discover it did. The film begins with two police officers discovering a little girl wandering around in the desert, then her family's destroyed trailer. Though most people nowadays know the surprise enemy (they're giant ants), it's easy to see how the audience of 1954 would have been strung along. And knowing doesn't make the moment of revelation any less scary. Much like knowing it's a shark in Jaws doesn't lesson the terror the beast inspired - most especially off screen. The director, Gordon Douglas, seems to have had the same idea as Spielberg. The ants look fairly cheesy, but they're used sparingly turning the film into more of a suspense movie rather than a creature feature.
The one sticking point in the plot is how quickly the scientific community figures out what's happening to the point of sending along 2 experts to look into the matter before anyone's even sighted an ant. But the experts, Drs. Harold and Patricia Medford, are well cast. Especially the daughter, who, though gorgeous, is no shrinking violet. She insists on entering the ant nest because someone who understands the creatures has to verify that no queens have left and her father's too old to go.
The scientific explanation of how the ants mutated into giants is consistent with ideas at the time. It's nice to see Japan wasn't the only country to come up with an atom bomb radiation monster flick.
The movie is also well known for being an early (though uncredited) role of Leonard Nimoy's. Look carefully. I thought for sure I'd be able to spot him and had to go back after the movie was done to find him (he's the airforce sergeant who makes a comment about Texans and the secrecy of the project they're working on).
It's a fun movie to watch but I'm glad no one's decided to do a remake of it. Yet.