What are big, brown, 12 inches long and make people scream?

Bats, of course.

And there’s no better place to learn about these peculiar nocturnal creatures than at the Organization for Bat Conservation. Its third-annual open house will be held from 11 a.m. to 4 p.m. Saturday.

The organization, which is located at 1553 Haslett Road in Haslett, was founded in 1990 by Kim Williams, an MSU graduate, and her husband, Rob Mies.

The nonprofit environmental education organization is one of a handful in the United States that specializes in bats.

“This is the only organization in the country licensed to care for these bats, and provide these types of educational programs,” Mies said.

The organization has 15 species of bats, and other nocturnal animals, such as lemurs, owls and flying squirrels. The open house will display vampire bats, nectar-feeding bats and fruit bats that have wingspans of up to 4 feet.

The organization specializes in the conservation of all bats, including the big brown bat, which is one of the few species that makes its home in Michigan.

The big brown bat can be found throughout North and South America, as well as the Caribbean. It has a 12-inch wingspan and a 3-inch torso.

Some experts say the creatures can be an important part of the Michigan ecosystem. The big brown bat only eats insects, and can devour thousands of them each evening. Many of bats’ favorite meals are those insects considered to be a nuisance by humans: mosquitoes, flies and gnats.

Bats are also a necessary predator in local agriculture because they feed on moths and beetles that destroy crops, said Richard Snider, chairperson of the Department of Zoology.

Snider has invited the organization to his Zoology 369, Introduction to Zoo and Aquarium Science, class for the past three years.

Snider said the it is an important animal organization in the area and should be appreciated.

“They keep the interests up in bats and in animals in general,” Snider said.