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Editor's note: The following article is part of Arkansas State University's science series, which is written by members of the ASU staff and published periodically by The Sun.

By Richard S. Grippo

That little winged ball of hair flying around a street light at dusk may be all that stands between you and a mosquito carrying West Nile virus.

While bats are often misunderstood and vilified, they are among nature's most efficient insect removers. The little brown bat, a common night flyer in Arkansas, can devour up to 1,200 insects in one hour.

Bats do more than eat bugs, however. Fruit-eating bats in South America drop seeds that grow into new trees. Nectar-eating bats transport pollen and pollinate plants just like honeybees. Bats, however, pollinate night-blooming plants that are not visited by the sunlight-loving bees. Meat-eating bats use vision, echolocation and sound from their prey to capture frogs and fish.

Of the almost 1,000 known species of bats, only three species are vampires. Thankfully, none of them live in Arkansas.

In addition to their various appetites, bats also come in many shapes and sizes. The largest bats have a wingspan of almost six feet. Other bats weigh less than a penny.

One common feature of all bats is the presence of large ears. These highly developed organs are used for echolocation, which gives bats the ability to detect the reflection of their own high-pitched cries from potential food items or obstacles. In this way they can safely navigate a pitch-black forest or locate tiny flying insects. This makes the myth that bats can get caught in people's hair silly. After all, how could an animal that can find and capture a mosquito on the fly be so clumsy as to fly into a person's head?

Bats are the only true flying mammal, however they are not flying mice. Bats belong to the group of mammals called chiroptera ("hand-wing"), while mice are rodents. Also, unlike rodents, bats usually bear only one young per year. The baby bats cling to their mothers' body like tiny opossums and drink her milk until they are old enough to fly and catch insects on their own.

Because of their low reproduction rate, bat populations take a long time to recover if they are negatively impacted by human or natural causes.

Arkansas is unusually blessed with many scientists who specialize in the study of bats. These researchers have investigated everything from types of roost places (some in trees, some in caves) to where bats go to drink water (large lakes to tiny forest ponds and even swimming pools).

Over the years some Arkansas scientists have noticed a decrease in the numbers of bats. The precise causes are unknown but are thought to include habitat destruction, pesticide exposure and disturbance of roost sites (caves, old mines, hollow trees). Recently a new threat to Arkansas bats has come to light.

Researchers at ASU have been investigating whether bats contain mercury, a toxic trace metal thought to originate from coal-burning power plants. These scientists have found that mercury tends to be high in bats in the same areas where the element is high in predatory fish, such as largemouth bass.

What is the connection between bass and bats?

Both eat aquatic insects that may be carrying tiny amounts of mercury. The fish eat the swimming juvenile stage of these insects while the bats eat them in the flying adult stage.

Because a bat will eat more insects in a night than a fish will eat in two weeks it is not hard to see how mercury could become a big problem for bats.

Scientists continue to research ways to protect these insect-eating friends of the night.

For more information contact the ASU Department of Biological Sciences at biology@astate.edu.

Dr. Grippo is an associate professor of environmental biology at Arkansas State University.