What is your favorite ecological nightmare/killer animal movies

[MR.Torrance]

Some of my absolute favorite movies are ecological nightmares-here's my list:
1. Squirm
2.Frogs
3.Kingdom of the Spiders
4.Grizzly
5. Piranha
6.Night of the Lepus
7.The Thaw
8.Jaws
9.The Swarm
10.The Food of the Gods
11.Tentacles
12.Day of the Animals
13.Black Water
14.Sharktopus
15The Giant Spider Invasion
16.Megapiranha
17.Tarantulas the Deadly Cargo
18.Rattlers
19Destination Infestation
20.The Savage Bees

I cant think of many things scarier than being devoured. This is my favorite sub-genre. Now what's your favorites? What scares you?

I like alot of the one's listed here. As far as my favorites probably jaws, pirahna, empire of the ants, cujo, anaconda and more!!!

Anyone like Rogue? I thought that was a pretty good killer croc movie.