The 1970's saw a rejuvenation of horror films in cinema, some awful (Night of the Lepus), some good (The Abominable Dr. Phibes), some sublime (Alien), and some....well, you decide. In this last category, I offer up Frogs of 1971. I saw this in college (at the drive-in again; hey it was Lubbock, Texas and there's lots of there there) with a carload of rowdy guys from the dorm, and I don't think I have ever had such a good time. From the IMDb:
The 1970s was the era of disco, blaxploitation, and eco-horror (aka nature's vengeance). "Frogs" is considered the first eco-horror flick. A young Sam Elliott plays a photographer who visits a southern estate where the patriarch (Ray Milland) refuses to live in harmony with nature. The old man sprays chemicals all over the swamp with absolutely no regard for the plants or animals. So it only makes sense that the frogs -- in collaboration with the snakes, alligators, spiders, etc. -- are out to dispense some justice! On the plot's value alone, there's no reason to interpret "Frogs" as any kind of high-quality movie. We could interpret it as a warning about messing with the Earth (when you battle nature, you ALWAYS lose), or we could just view it as a plain old fun movie. Whatever the case, it's a pretty enjoyable flick, silly though it may be.
There's nothing particularly graphic although a lot is implied. Watching a woman about to be killed by a giant snapping turtle is a little unnerving, though. Scenes with the frogs are often hilarious - they are obviously being thrown on screen - and not as menacing as one might imagine. The lobby card is quite misleading in this regard, although if you wait past the credits, you get to see where it comes from.
Not surprisingly, YouTube has the complete film and it is embedded below. If you missed out on disco, try the next best thing - a 1970's eco-horror film. They don't hardly make them like this no more.