Horror films with tiny terrors?

I'm going to have to check these out- I can't imagine how slugs could scare people. 

I haven't heard anything about bees. I once watched an Outer Limits episode where a colony of intelligent alien bees created a human woman to act as a queen bee and seduce a guy. She ordered the hive to kill his girlfriend. 

The only other animal I can think of that I missed is scorpions. I once saw a Ray Harryhausen movie about giant scorpions but I haven't seen attacks of small ones. 

I am planning a Tiny Terror movie fest- thanks for all the replies. This is a genre all to itself.