Maine’s bat populations are at risk from an outbreak of white-nose syndrome, the fungus that has killed off bats across the Northeast, the U.S. Fish and Wildlife Service announced Tuesday.

This spring, two of three caves in Maine that are known to house bats in their winter hibernation were found to contain the fungus, said John DePue, a biologist with the Maine Department of Inland Fisheries and Wildlife.

To keep the fungus from spreading, the state and the U.S. Fish and Wildlife Service are asking hikers not to go into caves, and asking homeowners who have attics where bats roost not to disturb them this summer.

White-nose syndrome, first discovered in New York state in 2006, is not a health threat to humans, said Ann Froschauer, a biologist with the U.S. Fish and Wildlife Service. But it has caused 90 percent to 100 percent mortality in bats at some of the infected sites across the Northeast, she said.

The syndrome, marked by a white fungus that appears on bat muzzles, is now found throughout the Northeast and Canada.

The effect on bat populations could be catastrophic, Froschauer said, and that could affect forestry and agriculture because of the role that bats play in limiting insect populations.

She said the little brown bat could be extinct in the region within 15 years.

“It doesn’t seem that there is something limiting the effect on the bat population,” she said. “We’re not looking at any time in the foreseeable future that small populations of bats that are left are going to repopulate to pre-white-nose-syndrome numbers.

“We don’t have a good sense if there is a point where it levels off. We’re not seeing that in the Northeast,” she said.

There are eight species of bats in Maine, with little brown bats the most numerous, DePue said. Little brown bats and northern long-eared bats are the two species infected in Maine, he said.

Five dead bats were found during spring surveys conducted by state biologists, DePue said. Subsequent tests showed that white-nose syndrome was the cause of death.

Two of the old mining caves where the fungus was found this spring are in Oxford County. A third, uninfected bat cave is in northern Maine.

One of the infected caves holds fewer than 100 bats, while the other holds 350 to 400 bats, DePue said. He would not disclose the location of the caves, to protect the bats.

Until last year, there was no evidence of white-nose syndrome in Maine, although it has been found in New Hampshire and, most recently, in Nova Scotia.

The fungus is spread by bats, and thrives best in moist areas with temperatures under 70 degrees, Froschauer said.

Federal biologists are hopeful that bats in the South and West will prevail, but it’s unknown whether that’s possible.

“It’s a cold-loving fungus. It loves cold temperatures,” Froschauer said. “There could be environmental conditions in the South and West that could affect how the fungus grows. We’re still learning a lot about it.”

– The Bangor Daily News contributed to this report.

Staff Writer Deirdre Fleming can be contacted at 791-6452 or at: [email protected]