Congressional members from 13 states are asking the Obama administration for emergency funding to keep bats alive.
The lawmakers want to find out why a fungus has killed an estimated half-million bats.
They say white nose syndrome has profound implications for public health, the environment and the economy because bats feed on bugs that spread disease and damage crops.
There is no evidence the fungus threatens humans.
Chris Tollefson of the U.S. Fish and Wildlife Service called white nose syndrome a priority for the agency, which has spent more than $750,000 on studies.
The states involved are Connecticut, Florida, Indiana, Massachusetts, Michigan, New Hampshire, New Jersey, New York, Pennsylvania, Texas, Vermont, Virginia and West Virginia.