A volcanic eruption and earthquake in Mexico ravages the countryside and opens a fizzure into a subterranean world. When citizens turn up missing it’s discovered that huge scorpions the size of tanker trucks are coming out of the hole and preying on the locals. An American and a Mexican scientist team up with a lady rancher to investigate and try to stop the killings, taking a perilous trip down into the bowels of the earth, where they witness battles to the death between oversized spiders, clawed worms, and scorpions. They seal the fizzure opening, but then find that several of the giant scorpions have escaped and are making their way towards Mexico City, devouring anything they come across. They attack a commuter train and peel the cars apart like bananas to eat the humans inside, but this is where the largest of them, a black 100-footer, turns on its smaller brethren and kills them all. The lone black scorpion goes on to the city where it engages in a violent battle with the Mexican Army’s tanks and helicopters in the city’s Colisseum before being electrocuted. As a big fan of Willis O’brien and Ray Harryhausen’s stop-motion animation work, I was impressed with this low-budget monster flick as a youngster and remain so to this day. I found it on VHS a couple of years ago and was pleased to see it released on DVD recently (along with Harryhausen’s “Beast From 20,000 Fathoms” and “Valley of Gwangi”). The budget for this movie is bare-bones and the acting and story dull, but the effects are incredible! O’Brien pulled out all the stops here and I’ve seen nothing in the genre more effective. The scenes in the cavern where the monster insects prey on each other and the human interlopers would raise the hair on anyone, and the attack on the train is absolutely nightmarish. The final battle between the black scorpion and the mechanized army is a tour de force, though the miniscule budget is glimpsed here and in a couple of other shots in the use of looped reels, repeated for padding. But if you’re a fan of this stuff BUY IT. You won’t be disappointed. Trivia Detail: I read in a review of the DVD release recently that O’Brien made use here of the spider models filmed in the “lost” cavern floor sequence in “King Kong” which was then edited out for being too scary.