Go bats!

What animal can eat 600 mosquitoes an hour at night, and ensure that you'll have bananas for breakfast in the morning? Yes, bats.

"People may already know that bats eat gobs of insects," says bat expert Jane Winchell, "but how many know that they are also among the best pollinators in the tropics and responsible for mangoes, bananas, peaches, and avocados?"

Ms. Winchell loves bats. She even let one sleep in her refrigerator! (More on that later.) So the natural-history curator at the Peabody-Essex Museum in Salem, Mass., goes batty when people say bats are dirty, blind, and likely to get tangled in your hair.

"The fact is," Winchell states, "bats are groomers and preeners. They clean themselves as well as cats do. They lick their thumbs to clean their ears....

They're not blind, either. "These flying mammals rely on sight, smell, and listening," Winchell says. "They know exactly where you are."

Merlin Tuttle, who founded Bat Conservation International in Austin, Texas, agrees. Bats are too good at navigating to get tangled in your hair, he notes. Using echolocation -high-pitched sound -bats can dodge a wire that's only 0.04 inches thick. With their supersensitive ears they can hear a caterpillar crunching on a leaf.

Bats inhabit every continent except Antarctica. You may think there are no bats near you, but perhaps you just haven't seen them. Bats come out only at night. Next to snakes, they are perhaps the most misunderstood animal in the world. Bats are also very important.

Most bats (7 out of 10) eat insects, catching them in their mouth or with a wing. Bats are excellent, agile flyers. The biggest colony of mammals in the world lives in Bracken Cave, north of San Antonio, Texas. There, a nursery colony of 20 million to 40 million Mexican free-tailed bats eats an estimated quarter-million pounds of insects on a summer night. That's as much as 125 cars weigh!

The bats also feast on the corn ear-worm moth. It's the No. 1 crop pest in the United States, if you count its cost to farmers. The moths lay eggs on corn and cotton crops. The eggs hatch into larvae that feast on the plants - but not if the bats feast on the moths first.

In the tropics and in the desert, some bats eat flower nectar and pollen the way bees do. And, like bees, these bats pollinate plants as they feed. (Bananas, for instance, begin as a large cluster of small flowers on a thick stem. After pollination, each flower develops into a banana. Look at the dark-brown tip of an unpeeled banana: That's where the flower was.)

"The more people know about bats," Dr. Tuttle says, "the more they'll care about them."

Fruit-eating bats spread seeds throughout the rain forest. More than half the fruit seedlings in those areas can be traced to bats. Some large fruit-eating bats damage orchards, though. The world's biggest bat is the flying fox. It is native to most tropical regions except South America, and is common to the South Pacific. Fruit-eating flying foxes grow to be about a foot long and have a wingspan of up to six feet.

And the world's smallest bat? The Kitti's hog-nosed bat of Thailand is about the size of a bumblebee!

Out of the 1,000 or so species of bats, only three are vampire bats. These blood-eating bats live in South and Central America. They used to be rare, but the clearing of rain forest for cattle ranching has increased their food supply. The bats' bites are very small, and the victims - mostly horses and cattle - hardly feel them. But ranchers are concerned because bat bites are associated with the spread of disease.

Vampire bats are surprisingly friendly and intelligent, it turns out. One researcher studying vampire bats found that they began to "hug" (not bite!) her hand in greeting when she reached into their cage. That's how the bats greet one another.

WINCHELL, Tuttle, and other bat-lovers hope that you will develop a "bat" attitude. That way, lots of bats will have safe places to do what they do best: eat insects.

Bats don't build nests, you see. They need hollow trees, caves, attics, or abandoned mines in which to live. Old mines are often considered a hazard, so they are sealed up. Today, "bat gates" are being installed in the mouths of old mines. The metal gates let the bats come and go, but keep people out.

You can help, too. "A bat house or nursery is a great way to appreciate the animals from a distance," Winchell says. Sometimes it takes a while for bats to find a house, and scientists are still figuring out what bats like. They do know they like it hot - up to 110 degrees F. for bat mothers nursing new pups. When adult bats go out to find a meal, the baby bats need to stay nice and warm.

Early spring - right now - is the best time to make and put up bat houses so migrating bats will find them. You could have a colony by June, but it's more likely you'll have to be patient. "It may take a few years," Winchell says.

And the bat in her refrigerator? It was a hibernating bat that woke up too early and flew into a house. The homeowners got in touch with Winchell, and her husband rescued the bat. But it was too cold outside to set it free. What to do? She fed it some mealyworms and let it drink some water, then put it in her fridge - the perfect artificial cave! She set him free that spring.