Overview
The White-nose Fungus (Pseudogymnoascus destructans), formerly known as Geomyces destructans, is a cold-loving (psychrophilic) ascomycete microfungus responsible for white-nose syndrome (WNS)—one of the most devastating wildlife epizootics in recorded history. Producing delicate, powdery white mycelial mats that coat the muzzles, ears, and wing membranes of hibernating bats in cold subterranean caves, this microscopic fungus has reshaped cave ecology across North America since its accidental introduction from Europe.
Biology and Physical Characteristics
Pseudogymnoascus destructans is an obligate psychrophile, growing exclusively in cold temperatures between 4°C and 15°C (39–59°F) with high relative humidity exceeding 90 percent—environmental conditions precisely matching typical limestone cave hibernacula. At temperatures above 20°C, the fungus ceases growth entirely. Under the microscope, it produces distinctive curved, sickle-shaped asexual spores (conidia) borne on branched conidiophores. The fungus secretes specialized destructive endopeptidases that digest living epidermal keratin, collagen, and dermal connective tissues, eroding the delicate wing membranes of dormant bats.
Behavior and Ecology
In Eurasia, native bat species have co-evolved with Pseudogymnoascus destructans over millennia, maintaining immune tolerances that prevent fatal tissue destruction. However, when the fungus was accidentally transported to New York caves around 2006, it encountered naive North American bat populations. The fungal mycelium invades wing tissues, triggering frequent premature awakenings from winter torpor. These repeated arousals cause hibernating bats to rapidly exhaust their precious winter fat reserves months before spring insects emerge, leading to mass starvation and dehydration.
Conservation and Human Impact
Since its arrival in North America, Pseudogymnoascus destructans has killed an estimated six to seven million bats across over 40 US states and Canadian provinces, driving species like the northern long-eared bat and little brown bat to the brink of regional extirpation. Biologists, wildlife agencies, and cavers enforce strict cave decontamination protocols, apply probiotic anti-fungal treatments, and install thermal cave warmers to help surviving bats fight off the fungal invasion.
Interesting Factoid
This fungus only grows in the freezing cold of dark caves and dies if it gets warm—it grows directly on sleeping bats like white powdered sugar, causing them to wake up and burn all their winter fat weeks before spring arrives!
Last updated: October 2026