Animals have every right to rip our faces off and frolic in our splayed viscera, and these films usually attest to the fact by playing out the nightmares emerging from our guilt. The films sometimes lack subtlety in conveying the ostensible motive for the rebellion. In Frogs, for instance, didacticism assures us that poor treatment and pollution are the prompts. Unfortunately, such didacticism is usually dismissible: e.g., I don't work for Dow Chemical nor teach 9th-grade Biology. Often though, the legitimate gripe is only hinted at, and this usually has a more impressive filmic and psychological impact. In Hitchcock's The Birds, part of the horror is that the bizarre avian viciousness seems arbitrary; but pay close attention to those brief moments involving caged songbirds and orders of fried chicken.
Monster From Green Hell (1957) -- radioactive wasps from African rocket wreck.
Attack of the Crab Monsters (1957)
The Fly (1958)
The Return of the Fly (1959)
The Wasp Woman (1959)
Attack of the Giant Leeches (1959) -- in a southern swamp.
The Giant Gila Monster (1959) -- in northern Texas.
The Killer Shrews (1959) -- dogs in shrew costumes.
Doctor of Doom (1962)
The Birds (1963) -- Hitchcock.
The Night of the Grizzly (1966)
Night of the Bloody Apes (1968)
Frogs (1972) -- and lots of them.
SSSSSSS (1973) -- watch for the weresnake at the sideshow.
Jaws (1975) -- of a shark.
Food of the Gods (1975)
Bug (1975) -- Bradford Dillman vs. large pyromaniac cockroaches.
Devil Dog: The Hound of Hell (1976)
The Savage Bees (1976)
Empire of the Ants (1977) -- Joan Collins and real estate; H.G. Wells story.
Day of the Animals (1977)
Orca: Killer Whale (1977)
The Pack (1977)
The Bees (1978)
The Swarm (1978) -- African killer bees in the U.S.
Jaws II (1978)
Il Fiume Del Grande Caimano (1979) -- a.k.a. Alligators or The Big Caimano River or Big Alligator River
Island Claws (1980)
Piranha Part II: The Spawning (1981)
Dogs of Hell (1982) -- Bad Cerberus! Bad dog!
Jaws III (1983)
Of Unknown Origin (1983)
Rats: Night of Terror (1983) -- Post-apocalyptic 2225.
In The Shadow of Kilimanjaro (1986)
The Fly (1986)
Jaws: The Revenge (1987)
Hell Comes to Frogtown (1987) -- Frog mutants discourage human reproduction.
The Nest (1988)
Slugs: The Movie (1988) -- okay, here's one at last I can't watch.
Pet Sematary (1989)
The Fly II (1989)
Stephen King's 'Graveyard Shift' (1990)
Pet Sematary II (1992)
Man's Best Friend (1993)
Mosquito (1995) -- the chain-saws seem unwieldy.
Deadly Invasion: The Killer Bee Nightmare (1995) -- Robert Hays.
Tremors II: Aftershocks (1996) -- giant man-eating worms in an oil field.
Mimic (1997) -- entomologist creates anti-roach bugs that like flesh.
Lake Placid (1999) -- paleontologist vs. killer crocodile.
Silent Predators (1999) -- hybrid rattlesnakes in California, of all places.
They Nest (2000) -- Maine island infested with lethal insects.
Boa (2001) -- prison inmates are prey in the Antarctic.
The Rats (2001) -- exterminator and PR exec vs. NY department store infestation.
Fangs (2001) -- genetically engineered bats.
Pythons 2 (2002) -- 57-foot snake mutants on killing spree.
They Crawl (2002) -- mutated cockroaches.
Sasquatch (2002) -- a rescue team witnesses the creature.
Threshold (2003) -- alien DNA mutates humans into insects.
Snakehead Terror (2004) -- mutated fish.
Boa vs. Python (2004) -- big snake showdown.
Bite Me! (2004) -- Bio-engineered marijuana with bloodthirsty insects.
Kaw (2007) -- flock of ravens.