(Harrisburg) -- Bat colonies in some areas of the state have been devastated by white-nose syndrome. An effort is underway this summer to track the number of bats still around. White nose syndrome has killed off more than a million hibernating bats in Pennsylvania and 17 other states as well as Canada since 2006. The fungus causes bats to exhibit uncharcteristic behavior during the winter and die off. Now, the state Game Commission is looking for the public's help in monitoring bat colonies. Spokesman Jerry Feaser says volunteers are being asked to collect data this summer by checking out nesting places like barns, steeples and abandoned homes. "White nose syndrome primarily kills during the winter. But, the true impact of white nose syndrome on bat populations can't be determined using estimates from those winter (habitats) alone," he says. "We need to look at the tradional bat maternity colony areas in order to understand the true impact." The disease exists in several areas in the commonwealth including Mifflin County -- where it's been found in several caves. Feaser says white nose syndrome could have big implications for public health, the environment and the economy because bats feed on bugs that spread disease and damage crops.