Devouring 1,000 Mosquitoes an Hour, Bats Are Now Welcome Guests as Zika Fears Rise

As mosquito season heats up, bringing with it the threat of the West Nile and Zika viruses, one Long Island town is taking an unorthodox approach: bats.

The town, North Hempstead, has approved the construction of boxes that function as bat houses in several parks to attract more bats to the area.

“Bats can eat up to 1,000 mosquitoes per hour,” Judi Bosworth, the town supervisor, said. “That’s extraordinary. A pesticide couldn’t do that.”

The town started encouraging the building and hanging of bat houses in its parks in 2007 to curb the use of pesticides, and it has added a few more each year since.

“We have an increased sense of urgency in terms of wanting to make sure that we’re controlling the mosquito population to the very best of our ability,” Ms. Bosworth said, alluding to the viruses. “Just having bat houses isn’t going to be the answer, but at least it’s looking toward a solution that is environmentally friendly.”

Over the years, the Boy Scouts and Girl Scouts have chipped in and built some of the houses. This year, Yianni Biniaris, 16, from Manhasset, N.Y., hopes building, repairing and replacing bat houses at the Clark Botanic Garden here will help him attain the rank of Eagle Scout. His project has been approved by North Hempstead, but it still needs to be cleared by the Scouts.

“Using the bat houses is more of a friendlier way of getting rid of mosquitoes, while saving the bat population,” Yianni said last month at the garden, home to about 20 of the houses.

His mother, Stella Biniaris, said wanting to remove bats from behind the shutters of their house had led her son to the project.

“We went to get rid of them and my husband said: ‘You can’t get rid of them! You don’t understand, we need them!’” Ms. Biniaris recalled.

The myths surrounding bats have long shaped public perception of the night creatures.

“I grew up and I always heard, you know, these old wives’ tales, that bats will swoop down on your head and get tangled in your hair,” Ms. Bosworth, the town supervisor, said. “Bats really have been very maligned.”

As for drinking blood, the bats on Long Island do not partake. New York State is home to nine bat species — none of them vampire bats, according to Dr. Liliana M. Dávalos, an associate professor in the department of ecology and evolution at Stony Brook University.

And less than one-half of 1 percent of all bats in North America carry rabies, according to the Humane Society of the United States.

The “strenuous aerobic exercise” of flying, Dr. Dávalos said, requires bats to pack on calories, searching for the most caloric prey available. Mosquitoes are not necessarily the most caloric — they are on the lower end of that scale — but bats will eat the ones in their paths anyway, she said.

Aedes albopictus, known as the Asian tiger mosquito, is found on Long Island and is capable of transmitting Zika in a laboratory setting, said Dr. Susan Donelan, an infectious disease specialist at Stony Brook, which is part of the State University of New York system. So far, there have been no reported cases of local transmission of the disease, she said.

For Zika to reach Long Island, an infected person would probably have to come to the area and be bitten by a mosquito that can transmit it, Dr. Donelan said.

“Mosquitoes don’t travel long distances; people do,” she said. “It’s not like the mosquitoes from Brazil are flying up here and infecting us. It’s the people that are coming from those areas.”

The West Nile virus, which is also spread by mosquitoes, appeared in the United States in 1999, according to the United States National Library of Medicine. As of October, 490 cases of West Nile and 37 deaths resulting from it have been recorded in New York since 2000, according to the State Health Department.

So the bats, with their appetite for mosquitoes, make very welcome neighbors. “These bats have helped us for so many years, we are in their debt,” John Darcy, North Hempstead’s deputy parks commissioner, said.

But how helpful are the bat houses?

“The effectiveness of bat boxes is hard to quantify,” Kevin Braun, the town’s environmental control specialist, said. “But we know that bats eat flying insects, including mosquitoes, so it is not a great leap of faith to say that more bat boxes means more bats and less mosquitoes.”

Eric Powers, a biologist who conducts wildlife workshops, said, “We know that it works because of the myriad trials around the country where these boxes are in place and bats are busy eating their way through the bugs.”

At the Clark Botanic Garden last month, Mr. Powers said that in an ideal world, bats would live in dead trees with peeling bark, or in old barns.

“But here on Long Island, it’s such a dense population that the second that a tree is identified as diseased or aged, it’s cut down and removed,” he said. “We’ve eliminated all the places that they would like to hang out.”

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