I think you'd visit butterflies at the butterfly petting zoo.
New2, I always thought "ant farm" was sort of "tongue-in-cheek," but they've been around since I was a child.
I think they raise worms for bait in worm farms, but I'm not sure. I recall a few years back a rumor was started that McDonald's used earthworms to fortify their hamburgers. It was a rediculous idea, because earthworms are worth more per pound than beef - better quality protein too.
Many years ago, Knott's Berry Farm (originally for raising berries - still a famous brand of jams and jellies) was converted to a theme park, competing with Disneyland in Orange county. I think they've only recently removed the "farm" from the name.
(Am I going to be in trouble for naming names? Should be XYZ Theme Park?)
People get creative with names for commercial zoos. There's "Lion Country Safari" in San Diego, or near San Diego. I recall "Benson's Wild Animal Farm" in New Hampshire. I think some are called "parks," but I can't think of one specifically at the moment.