CHARLESTON, W.Va. (AP)  The federal Forest Service is preparing to close thousands of caves and former mines in national forests in 33 states in an effort to control a fungus that has already killed an estimated 500,000 bats.

A Forest Service biologist, Becky Ewing, said an emergency order was issued last week for caves in 20 states from Minnesota to Maine. A second order covering the Forest Service’s 13-state Southern region should be issued this month.

The sites will be closed for up to a year, Ms. Ewing said.

The orders follow the request in March by the Fish and Wildlife Service for people to voluntarily stay out of caves in 17 states.

Bats have been dying at alarming rates from what scientists call “white-nose syndrome,” so named because it appears as a white powder on the face and wings of hibernating bats. The problem was first spotted in New York and in two years has spread to caves in Virginia and West Virginia.