(CNN) — Bats used to be thought of as spooky flying creatures, denizens of nightmares and scary stories -- but now we know that they are an incredibly important part of their local ecosystems.

They pollinate crops, devour pests (especially mosquitoes) and their guano is a valuable fertilizer. On top of all that, many types of bats put on a spectacular show every evening as they emerge from their caves, twirling and whirling into the evening sky.

The next time you find yourself in Austin, Texas, you can witness this for yourself, right in town.

There, you can see Mexican Freetail bats fly out from their "cave" -- the concrete undercarriage of the Congress Avenue Bridge, where their evening exit flight is a popular local attraction. At sundown they zip out from under the bridge and fly east along the river, to Texas' capitol building.

"Austin loves its bats," says Mylea Bayless, a senior director at Bat Conservation International.

It's that love that leads true devotees to Bracken Cave, a half-moon shaped slit in the earth about 70 miles south of Austin.

There, bat fans can experience "...one of the most spectacular wildlife events that you can see anywhere," says Bayless. "It's the largest congregation of bats in the world, and they come out of this cave by the millions."

The bats will keep flying out of the cave for hours -- so many that it takes 3-4 hours before they all exit their cozy home beneath the ground.

"They'll circle up like a giant tornado into the sky, and they'll fly out over the corn and cotton fields eating agricultural pests," says Bayless.

Visitors can watch as more than 30 million of the tiny dancers zoom out of the cave at high speed -- and will hear the special clicks as they use their echolocation abilities to expertly avoid flying into each other.

Bayless calls most of the common fears about bats -- that they will get tangled in your hair, that they will run into you, that they all carry rabies -- myths and misconceptions.

She encourages people to come out and see the bats and how they behave for themselves, and make judgments about them after experiencing their nightly show and learning a bit about them.

The best times to visit Bracken Cave are July and August when days are longer, and also because baby bats are born in June and start flying in July.