MISSISSIPPI STATE -- Bats have a mystique about them, but wildlife experts say the flying mammals do not threaten humans and are one of mosquitoes' worst enemies.

There are about 27 species of bats in North America, and eight of these are found in Mississippi. Bats here typically have brown fur, but some have red or gray coloring. Those species found locally are small, ranging in length from 3 to 5 inches with a wingspan of 8 to 12 inches. Bats have teeth and leather-like wings and tails.

Ben West, wildlife specialist with the Mississippi State University Extension Service, said bats live in areas where there is a water source and shrub woodlands to attract insects. Bats that live alone typically make their homes in crevices and under bark in trees. Bats that congregate in large groups often live in caves, under bridges or in attics where they cause problems for homeowners.

"When they get into attics, you may hear them scratching around, but mostly you know they are there because of the smell. Bat droppings are called guano, and have a very distinct odor of ammonia," West said. "Both the bats and the mess they leave are best removed by experts."

These experts can be found in the U.S. Department of Agriculture's Wildlife Services. Sometimes exterminators are called in, and people with bat problems can contact their local Extension offices for help. Bill Maily, Extension area agent with wildlife and fisheries headquartered in Hinds County, hears from many people with bat problems.

"Most of my calls come early in the spring when bats are breeding or late in the fall when they're looking for roosting places," Maily said. "Usually when they get into houses, it's older houses that were not built as airtight as modern homes and that often have large vents at the ends of the house."

Maily said homeowners can go outside at dusk to watch where the bats leave the house. Cover these openings with something like quarter-inch hardware cloth.

"If you can keep them from coming back in once, they usually find another place to roost," Maily said.

A light placed in a favorable bat environment can discourage them from roosting, and putting up bat houses can encourage them to locate outside.

West said moth balls, a popular home remedy for running out bats, don't work and are not legal for this use in Mississippi.

"Some studies have shown that in really high concentrations, moth balls will keep bats away, but the concentration is so high it's dangerous for humans, too," West said.

Some people worry about having bats in the area because they can carry rabies. West said that while they can transmit rabies to humans, in nearly every instance where this happens, the person tried to handle the bat with bare hands.

"Use a little common sense and this should never be a problem," he said.

The furry mammals eat mosquitoes by the thousands every night. According to Bat Conservation International, a single brown bat can catch 1,200 mosquito-sized insects in one hour.

"Bats are nocturnal and eat any insect that is flying at night," West said. "A lot of people put up purple martin houses because these birds eat mosquitoes, but they don't eat nearly as many as bats do."

Contrary to legend, bats are not blind, and West said they actually have good eyesight. However, they use ultrasonic sonar to locate their prey and can hunt in total darkness. They often use their wings and tail to capture insects and throw them in their mouths.

Because bats are superb insect hunters, many people want them around. Homeowners can encourage nearby bats to call their yard home by installing bat boxes. These boxes can be built in a variety of shapes, but all are open from the bottom and have individual compartments inside for the bats to roost.

"Location is really important for bat houses," West said. "Bats prefer warm areas, so in Mississippi, they need to be in the sun for about six hours a day. If bats are in the area, a good bat box can offer them just the incentive they need to stay close to your house."