First, a few ground rules: No dinosaurs. They're supposed to be big. There is nothing unusual about a big dinosaur. Now, a giant ant, that's a different story. And we'll relegate the scope of our scrutiny to the 1950s, thus eliminating Mothra, Konga, and a horde of others. Sadly, this also excludes King Kong, but he's received more than his share of critical attention over the years.

10. Giant Gila Monster (1959)
Ken Curtis and Ray Kellogg, the production team who brought you the Killer Shrews, fashioned this flimsy story of a big lizard marauding through a desert town. For once, nukes weren't to blame for the scaly killer's tremendous size. It seems that minerals in the soil ignited his growth spurt -- or at least the sheriff thinks so. Countless Matchbox cars were destroyed during filming. Not a good movie, but a fun one.

9. The Black Scorpion (1957)
Stop-motion pioneer Willis O'Brien of King Kong fame, animated the titular menace. His efforts are largely spoiled however, by close-ups of the scorpion's papier-mache head that make him look as though he'd overdone his mascara that morning. Thank God stalwart Richard Denning is on hand to save the day -- and nearly the film.

8. The Deadly Mantis (1957)
The one real clunker of producer William Alland's prodigious output, which included beloved titles such as Creature From the Black Lagoon and It Came From Outer Space. Process shots of the mantis on the march are never convincing and often humorous, and grainy stock footage of fleeing Eskimos hardly bolsters credibility. Hero Craig (Peter Gunn) Stevens is eventually able to fry the big bug after sealing him in the Holland Tunnel.

7. Amazing Colossal Man (1957), War of the Colossal Beast (1958)
Both Amazing Colossal Man and its seamy sequel, War of the Colossal Beast, were produced by the king of drive-in gigantism, Bert I. Gordon. He and his wife Flora are responsible for the rather crude process shots, and in many scenes we can see right through the big, bald giant. In the initial film, he's blown from the Hoover Dam by a barrage of cannon fire. In the follow-up, he commits high-voltage hari-kari by seizing an electrical line.

6. The Spider aka Earth vs. the Spider (1958)
Gordon strikes again with this torpid tale of an outsized spider emerging from his cave to terrorize a small town. At one point, his dazed carcass is dragged to the high school gym, where's he's reanimated by the wail of Skip Young's jumpin' rock band. Ed Kemmer strives to bring credibility to the goings on and, all told, what emerges is one of Gordon's more enjoyable films.

5. Beginning of the End (1957)
A horde of gargantuan grasshoppers is poised to devour Chicago in a film devised and directed by -- who else -- Bert I. Gordon! B-horror mainstay Peter Graves is on hand to lead the counter-assault on the windy city, luring the large locusts into the depths of Lake Michigan. Gasp as several postcards depicting the Wrigley building are nearly devoured by the marauding insects.

4. Them (1954)
First and maybe the most intelligent of the big bug movies, this film is structured more like a murder mystery than a flat-out horror flick, with killings and clues gradually leading to the revelation that gigantic ants are responsible. A wonderful cast, including Edmund Gwenn, James Whitmore, James Arness and Joan Weldon, lends immeasurably to the film's allure. In retrospect, the big ants are a disappointment, but it's still a terrific ride.

3. Tarantula (1955)
Producer William Alland and director Jack Arnold deliver rock-solid thrills. Still among the scariest bug movies ever made, it's tautly paced and tempered with good performances from Leo G. Carroll and John Agar. The desert's sense of mystery and seclusion is exploited to good effect, and the FX work holds up admirably. Clint Eastwood is the steely-eyed jet pilot who bombs the big arachnid into submission.

2. Giant From the Unknown (1958)
He's not a big bug or a nuclear-enhanced guinea pig. He's just a really big, really mean guy reanimated by a bolt of lightning after a 500-year snooze. Wouldn't that tick you off? Of all the films ever made about gigantic, bloodthirsty, zombie conquistadors, this one is easily the best. Its novelty endeared it to me years ago. Directed by no-budget maestro Richard Cunha (She Demons, Missile to the Moon), it features a familiar cast that includes Ed Kemmer, Morris Ankrum, Sally Fraser, Bob Steele and, sporting make-up created by the legendary Jack P. Pierce, Buddy Baer as Vargas the Giant.

1. Monster That Challenged the World (1957)
Not a bug, not an arachnid, but a giant mollusk spawned in the depths of California's Salton Sea. Tim Holt leads another likable cast that prominently features Hans Conried in a serious turn as a frazzled scientist. Scenes of the king-size caterpillar capsizing boats are quite effective. Director Arnold Laven dishes up the entire film with an applaudably atmospheric panache. It's puzzling that this movie is so often overlooked by genre critics and fans.