Here we take a look at one of my favorite early 70's "Ecological Horror" films
Frogs is a 1972 horror film directed by George McCowan. The film falls into the "eco-horror" category since it tells the story of an upper-class U.S. Southern family who are victimized by several different animal species, including snakes, birds, and lizards, as well as the occasional butterfly. Nature, the movie suggests, may be justified in exacting revenge on this family because of its patriarch's abuse of the local ecology
Pickett Smith (Sam Elliott) rows in a canoe and takes photographs of various animals in a swamp from around the Crockett family's estate; a scenic plantation located on an island on a lake in rural Florida. After Clint (Adam Roarke) accidentally tips Pickett's canoe over, he and his sister Karen (Joan Van Ark) escort Smith to the family mansion where he meets the entire Crockett family. The grouchy, wheelchair-bound patriarch, Jason (Ray Milland), intends on spending the next day enjoying both the 4th of July and his own birthday celebrations uninterrupted. Due to the mutual dislike of the fauna around the mansion, Jason has sent a man called Grover to spray pesticide in order to get rid of the amphibians. Pickett discovers Grover's corpse covered in snake bites in the swamp not far from the house. Despite this warning, Jason continues with his celebrations the next day, unaware that the frogs and other animals plan to get revenge for the constant pollution around the area.
On the mainland, Michael checks the telephone lines in his car (when the phone line is dead) but is distracted by birds. Hoping to shoot them down, he chases them but accidentally shoots himself in the leg. A swarm of tarantulas cover him with webbing and moss, cocooning him completely.
On the island, Kenneth leaves to get flowers from the greenhouse but lizards infest the greenhouse and knock over jars of chemicals. The mixture fills the place with poisonous gases and Kenneth asphyxiates.
Seeing the danger posed by the animals, Pickett suggests that everyone should try to leave the island, but Jason is adamant that nothing will ruin his day. Meanwhile, Iris is lured into the path of several frogs and snakes while chasing after a butterfly. Trying to escape, she falls into a small swamp of leeches which latch on to her until she manages to pull them off. Massively fatigued, she falls near a rattlesnake which promptly bites her and kills her. Her husband Stuart comes looking for her, only to meet a grisly end when he falls into the swamp and is eaten by an alligator.
Charles and Maybelle, Jason's long-suffering butler and cook, decide to leave along with Kenneth's fiancee, Bella, on Pickett's advice. Clint takes them across the lake in his speedboat. Clint stays behind and searches the nearby grocery store while the others walk on. They are soon attacked by birds and pecked to death offscreen. Clint discovers his boat has been untethered and swims to reach it but a water moccasin kills him in the water. His wife, Jenny, witnesses this through binoculars and attempts to rescue him, but gets stuck in the lake mud and is killed by a large snapping turtle.
Karen and Pickett decide to leave with Clint and Jenny's kids and leave Jason behind, his mind still intent on celebrating. They cross the lake in Pickett's canoe encountering alligators and more water snakes, which Pickett dispatches with the boat paddle as well as a shotgun. They eventually make it ashore and to a road where they hitch a ride with a woman and her son. While the woman tells the four survivors that they are driving towards Jackson City and have strangely not seen a single person or car on the road all day, the boy shows them a huge frog he took from summer camp where his mother picked him up...
Later that night, Jason, now alone in his mansion (save for his dog Colonel), witnesses hundreds of frogs breaking their way into the house and staring at him. Looking around the room at his stuffed animal trophies adds to his tension and he collapses out of his wheelchair from a heart attack. The frogs croak louder and louder as they hop over his corpse. The final shot shows all the lights in the mansion flickering out for good... implying that nature has won, and the rest of the humanity is apparently next. A post-credit scene shows an animated frog swallowing a human hand before hopping off-screen.