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Bats

A hoary bat hanging upside down from tree branch

Bats are a highly specialized group of mammals that are often misunderstood. There are over 1,300 bat species worldwide and at least 12 species in West Virginia. West Virginia bats range in size from the eastern small-footed myotis (4.5 grams) to the hoary bat (27.5 grams), with the average size of a bat in West Virginia being about 10 grams.

All 12 species of bats found in West Virginia feed on insects. They are voracious eaters, consuming 50 to 75 percent of their body weight in insects each night.

A primary predator of nocturnal insects, bats can suppress populations of forest and agricultural pests. While one bat consuming between 5 and 7.5 grams of insects a night may not sound like much, consider that there may be 100,000 bats on the local landscape. The amount of insects consumed each night jumps to between 1,100 and 1,650 pounds.

Benefits of Bats

Bats provide a significant ecological service by feeding on insects and removing agricultural pests, including those capable of transmitting pathogens to humans from the landscape.

The size of a bat’s prey depends on the size of the bat and can range from 1 millimeter (midges and mosquitos) to as large a 50 millimeters (beetles and large moths). Many species of agricultural pests have been found in the diets of bats including June beetles, click beetles, leafhoppers, plant hoppers, spotted cucumber beetles, green stinkbugs and corn earworm moths.

Published estimates of the value of pest suppression from bats averages about $74 per acre; therefore, their value to the U.S. agricultural industry is about $22.9 billion per year.

Dangers of Bats

While bats do provide a valuable economic service by consuming insects, they can become a nuisance when they roost in domestic structures.

Like all warm-blooded mammals, bats can carry rabies, and a fungus that causes histoplasmosis in humans can grow in deposits of guano (feces) that can build up beneath bat roosts.

Most commonly bats enter houses through small openings or cracks around the roof and eaves. While bats can be excluded from houses, care must be taken to ensure that no bats are trapped inside as they could find their way into the residence or die and create bad odors. It is also important to time bat removal or exclusion to ensure that non-flying bats (young of the year) are not left inside.

Because of these considerations and the disease concerns associated with bats, it is recommended that only trained, immunized professionals work on bat removal and exclusion projects.

If you suspect bats are roosting in your home or outdoor structure, please contact the local West Virginia Division of Natural Resources office or private nuisance wildlife control operator for assistance.

Decline in Bat Populations

Currently, several bat species are facing significant population declines from an introduced disease called white-nose syndrome.

White-nose syndrome is caused by a fungus and impacts hibernating bats. In some hibernacula, hibernating bats have experienced 90 to 100 percent mortality. It is estimated that we have lost over 5.7 million bats in the eastern U.S. Not only are we losing these iconic species from the landscape, but we are also losing their suppression of our insects.

White-nose syndrome has been documented in West Virginia, and we are seeing the impacts of this disease in our bat populations.

West Virginians can help combat this population decline by:

  • Promoting bat conservation by understanding the ecological services that our bats provide and educating landowners of their importance.
  • Avoiding caves or mines where bats may be hibernating during the winter months. If you enter those caves or mines outside of the hibernation period, be sure to decontaminate your clothing or gear before you enter another cave to help stop the spread of the white-nose fungus.
  • Constructing bat houses to provide daytime roosting sites.

Author: Sheldon Owen, WVU Extension Wildlife Specialist 
Last Reviewed: April 2018