Enlarge By Al Hicks, New York State Department of Environmental Conservation via AP Bats are dying off by the thousands as they hibernate in caves and mines around New York and Vermont, sending researchers scrambling to find the cause of a mysterious condition dubbed "white-nose syndrome." STRANGE MARKINGS, BEHAVIORS STRANGE MARKINGS, BEHAVIORS "We really don't know what is killing these large numbers of bats," says biologist Jacques Veilleux of Franklin Pierce University in Rindge, N.H. "All we have are symptoms." He says that chiefly they are: White fungus on the wings of almost all the affected bats and on the faces of about half. Emaciation of the body-fat stores that bats typically live off of during hibernation. Clusters of hibernating bats migrating oddly close to cave entrances during winter. Starving bats leaving caves during the day in the winter. Biologists are stumped by a plague that has killed tens of thousands, and perhaps hundreds of thousands, of bats this year in Northeastern states. The cause of "white-nose syndrome," so named because of the white fungus that appears on bats' noses and wings, remains a mystery. And the plague is still killing bats, alarming scientists who had considered it a winter syndrome. "The surprise for us has been finding out that bats are still dying," says biologist Susi von Oettingen of the U.S. Fish & Wildlife Service office in Concord, N.H. Biologists combing summertime roosts report finding six species of bats affected by the syndrome in New York, Vermont, New Hampshire, Massachusetts and Connecticut, she says. "I'm continuing to get calls on a daily basis from cities and residents reporting dead bats," says Scott Darling of the Vermont Department of Fish & Wildlife. Spot surveys are being done in the five states, but conservation officials won't get a solid sense of further losses until later this month when male bats begin returning to caves, Darling says. One bat can eat more than a pound of night-time insects in a week. White-nose syndrome threatens the endangered Indiana bat, Darling says, and agricultural pest numbers may explode without bats. In the winter, ill bats appeared to burn up their stores of fat too early in hibernation; many others left the caves too early and froze to death. At a meeting of bat biologists in Albany, N.Y., last month, scientists agreed on a research plan to find out whether the syndrome's cause is a fungus, unknown disease or environmental contaminant. They received guidance from bee researchers, who are trying to unravel their own mystery syndrome, called colony collapse disorder, which has devastated the nation's bee population, says microbiologist David Blehert of the U.S. Geological Survey's National Wildlife Health Center in Madison, Wis. IN THE CAVES: Northeast bat population is in its own kind of hell MORE INFORMATION: White-nose syndrome First spotted in four New York caves in 2007, the bat syndrome spread to 24 caves by March, killing 90% of the bats in some locations. A big worry is that bats, which can travel hundreds of miles in the summer, will spread the syndrome, von Oettingen says. Researchers suspect Pennsylvania may be the next outbreak site. Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more