According to a report by wildlife authorities a mysterious disease that has killed thousands of bats in New York for two years has spread into New Jersey and Pennsylvania raising concerns of the possibility of an increase in bugs and pests.

The state Department of Environmental Protection's Division of Fish and Wildlife said in two caves in Morris County which served as a home to the furry insect-eaters during winter hibernation, hundreds of bats were found to be dying. Mick Valent, the division's principal zoologist said, "You can't start treating something when you don't know the cause of it."

He said several bats found last month later died while in rehabilitation, while others were found dead or emaciated with a white fungus around their muzzle, dubbed "white-nose syndrome". Biologists are at sea as to whether the fungus is a cause or symptom and the only fact that they are clear about is that the fungus and the deaths occur concurrently.

The "white-nose syndrome" was first noticed in early 2007 in New York and newspaper reports said the syndrome caused the bats to come out of their winter hibernation prematurely and as they flew out in search of food, with no insects to eat in that season, they burned stored fat and fell to the ground dead.

Many of the dead bats that were found inside three abandoned mines in Rockaway Township and Denville, where the majority of New Jersey's bat populations are located, were found with the fungus around their noses and wing membranes. This condition later spread to Massachusetts, Vermont and Connecticut.

"Nobody, at the time, knew what it was," Valent said. "They were just seeing unusual activity by bats, resulting in a lot of the bats dying. Nobody is completely sure what is causing this." He added that there is no indication that disease poses a risk to humans.

Experts feel if the bat population gets affected that could result in an increase of bugs and crop pests being seen while others worry about the spread of the disease as bats are highly migratory and fly in tight clusters of up to 200 or 300.

Carlos Iudica, biology professor at Susquehanna University and co-chair of an interstate committee investigating the problem said, "We're going to start paying a fortune for a tomato" if the trend continues.

Researchers said at least six of the nine bat species found in the Northeast appear to be vulnerable to the phenomenon in New York, Vermont and Massachusetts and the Pennsylvania Game Commissioner said Thursday the syndrome had spread into the state's bat population.