The Popularity of Bats Comes Home to Roost : Environment: Insect control and conservation are two reasons the bat population is flying high. Many are now defending the little mammals.

Ask the average person if he would be enthusiastic about having furry, flying bats in or around his home, and you’d probably get an emphatic thumbs-down. Ask him to actually encourage the mammals to live on his property for the sake of conservation, and he might even accuse you of having bats in your belfry.

The bat is one animal with which most people do not care to coexist. Yet, when it comes to pest control, it’s one of man’s best friends. Tom Ewing discovered that about a year and a half ago, when he invited bats to live at his bed and breakfast in Maine.

Located on Georgetown Island, Ewing’s property is surrounded by wetlands, a perfect breeding ground for mosquitoes. Ewing and his wife, Judy, tried a number of methods to rid the area of the blood-sucking insects. Concerned about health and the environment, they chose to avoid insecticides and pesticides and looked for more environmentally sound solutions. Learning that purple martins eat insects, the Ewings erected martin houses to encourage the birds to take up residence.

But they discovered purple martins were not the answer. In addition to eating only a small percentage of mosquitoes, the birds also ate beneficial insects such as dragonflies, which feed on mosquito larvae. A guest at their bed and breakfast suggested bats. One little brown bat, the most common of 40 species of bats found in the United States, is capable of eating 3,000 to 7,000 mosquitoes a night. With high hopes of reducing the number of mosquito welts on his body, Ewing sent for plans to build bat roosting boxes and erected a few on his property. Soon bats moved into the wooden houses. And life has been a lot more comfortable outside the Ewings’ bed and breakfast ever since, even with the little creatures diving and flapping around in the dark.

“Mosquitoes suck a lot more blood than vampire bats ever thought of sucking,” joked Ewing, who turned the solution to his mosquito problem into a business. Figuring others in his community might be just as eager to deal with mosquito problems without insecticides, Ewing decided to make more bat houses and market them. He sold 300 during his first summer in business. Today, his bat roosting boxes are featured in five mail-order catalogues and 160 retail outlets nationwide.

Ewing’s company, Coveside Conservation Products, sells six sizes, each constructed of one-inch, untreated white pine. Bats like to roost in a warm environment and pine retains heat, he explained. The smallest house, a single-celled box which he calls the “batchelor” pad, is designed for male bats, which tend to live in small groups or alone. His bat condo, the most popular, is a four-chambered unit that holds 30 to 50 bats--often a nursery colony of mothers and offspring. His six-chambered bat mansion holds up to 150 bats. He also makes two types of bat shelters. Designed for places like parks, they are capable of housing thousands of bats.

Ewing said that the majority of his customers purchase bat boxes for insect control. But a growing number are buying bat roosting boxes for conservation--they want to help save bats. According to Ewing, man is responsible for killing off about 90% of the world’s bat population during the last 20 to 30 years, mostly through the use of pesticides and the destruction of their natural habitats. With their favorite old houses, barns and hollow trees replaced by new housing or commercial developments, bats are experiencing a housing crunch.

Heidi Hughes, who sells bat boxes along with birdhouses and other supplies at her Rockville, Md. store, Wild Bird Co., was surprised by the demand for them when she opened her store five years ago. Bat boxes were the fastest-selling item during her first summer in business. She has seen awareness of their existence and benefits grow ever since. “When I first started my business, people would ask ‘Who would want a bat house?’ Now they say, ‘I want to see your bat houses.’ ”

Depending on who makes the boxes and their size, the cost begins at $20. Simple to construct, they can be made in a matter of minutes for considerably less. It looks something like a birdhouse, with a roof on top to retain heat, no openings on the sides and an open bottom for entry.

Chambers within the box create different heat zones, which bats will seek depending on the outside temperature. During warm weather months, bats spend most of their days in shelters, quietly hanging upside down. At night, they come out and feed on mosquitoes and other insect pests.

Unfortunately, convincing your neighborhood bats that the home you’ve given them is the home they should live in isn’t always a successful venture, warned Hughes, who is treasurer of the American Bat Conservation Society, an organization dedicated to the preservation of bats. “We can tell you how to get bluebirds into a birdhouse. But we don’t know enough about how to make bats come to a roosting box.”

Normally, bats leave their summer roosting spots in the fall to either hibernate or migrate, depending on the species. Bats are habitat-faithful animals, Ewing explained. Once they’ve found a comfortable home, they’ll return to it each year for up to 20 years. Hughes said it’s been discovered in recent years that the destruction of natural habitats for hibernation, such as caves and deserted buildings, is forcing some species of bats to remain in home attics year-round, much to the dismay of homeowners.

Both Hughes and Ewing said the average homeowner should have no trouble evicting bats if the points of entry are relatively small. Keep in mind that a bat can fit into an area no bigger than a thumbnail, so possible areas of entry should be scrutinized carefully.

Despite all the stuff in horror films, only 10 people have gotten rabies from bats in the last 40 years; in eight of those cases, the bites were provoked, Hughes said. In the United States, more than 10 people die annually from dog attacks. And in one mosquito season, more people are likely to die of encephalitis than from bat bites.

“It’s unfortunate that most people have had only negative encounters with bats,” Hughes said. “When you’re swinging a broom, they’re frightened. It’s only natural for them to start hissing and moaning and clashing their teeth. Consider that to a bat that weighs only about two ounces, it’s the person that looks like the monster. All bats want to do is just eat bugs and be left alone.”