Bat groups and cavers across the UK have been asked to report suspected cases of an illness that has killed bats in the US.
White nose syndrome makes it appear as if the animals' noses have been dipped in powdered sugar.
It wakes bats prematurely from hibernation and leaves small, white, fungal spots around the nose and mouth.
The Bat Conservation Trust is raising awareness of the condition in the UK, where no cases have yet been found.
The organisation has produced a guide to the syndrome on its website.
It includes advice on what to look for, how to record cases and where to send data.
The trust said: "If you see live or dead bats with white fungus, please do not touch them.
"Where possible, photograph the potentially affected bat, or bats, and exit the site immediately.
"Make an accurate recording of where the bat was found within the site and call the Bat Conservation Trust at 0845 1300 228 to report the incident."
In March, Massachusetts wildlife officer Tom French took BBC News to a mine where the bats should still have been huddled together in hibernation.
Some of the survivors showed clear signs of white nose syndrome, although others did not.