Living in Harmony with Bats
 | Author:
Allison Kosto, MSU Broadwater County Extension Agent
MSU Broadwater County Extension Agent |
Living in Harmony with Bats
Allison Kosto
MSU Broadwater County Extension Agent
Bats are often associated with Halloween and are the primary characters in several myths and spooky tales. In reality, bats are extraordinary creatures. They play a critical role in our ecosystem by controlling insect pests. One colony of bats can consume over 1,000 pounds of insects in one night. One study found that pest suppression from bats averages about $74 per acre, and their value to the U.S. agricultural industry is about $22.9 billion per year. In Montana alone, pest control of bats is valued at $680 million each year. Bats can also pollinate plants and distribute seeds. Even though bats are often silent creatures, they sometimes get a bad rap when they are found in the home. Steps can be taken to eliminate bats from a home and reduce encounters with humans.
In Montana, there are 15 species of bats. The most common bats are the big brown bat and the hoary bat. Bats in Montana migrate to follow the food supply. However, some bats only come to Montana during the winter. A few species are solitary but most congregate in groups called colonies. Bats are nocturnal. They roost during the day and fly and hunt at night. All bats in Montana feed on insects. A bat can consume one-third of its body weight in insects within the first half hour.
The two primary concerns with bats entering the home are disease and buildup of feces. Bats are well-known carriers of rabies which can be transmitted to humans. If you see a bat acting abnormally, such as fluttering on the ground, approach it with caution or leave it alone. Bats can be tested for rabies; The entire body must be sent to the lab so the brain can be tested. Bat feces, also called guano, has an odor when it builds up and decomposes. It also provides a location for fungi and bacteria to grow. In severe cases, guano can lead to stained ceilings and siding. It can also contaminate stored food or products.
The best approach to control bats is to completely eliminate them from the home. This can be easier said than done. Bats can enter buildings in openings such as vents, broken windows, holes in siding or around eaves. Smaller species of bats can crawl through slits as narrow as 3/8 inch, so any holes smaller than ¼ inch should be sealed. Holes can be plugged or covered with sheet metal or hardware cloth.
It is important to follow a methodical process to cover the holes, so you don’t seal the bats into the building. Start by observing the house about 30 minutes before dark. This is when the bats start to become active. Watch for locations where the bats exit. You should be able to identify one or two primary entrances. The next day, cover all the holes except the primary entrances. It is important to wait to cover the primary entrance until you know the bats have exited the building. Plan for this about 1 hour after dark. Wait a few days, re-open the entrance to allow any remaining bats to leave and then reseal it. Another option is to wait until the winter after the bats have migrated.
Repellents may be an option to provide temporary control of bats. Naphthalene is a chemical commonly used in moth and insect repellent and bats also dislike it. If the roost area such as an attic is accessible, you can use this material to drive them out. However, the chemical dissipates quickly and may need to be reapplied. Using bright lights to illuminate the roost can sometimes also be effective. Neither one of these methods is a long-term solution for bats but might be of assistance while a permanent solution is being developed.
Even as an unwanted guest in the home, bats have a significant positive impact on the environment. Unfortunately, several species are facing significant population decline due to a disease called white-nose syndrome which is a fungus that affects hibernating bats. It can result in 90 to 100 percent mortality. It is estimated about 5.7 million bats have been lost in the Eastern U.S. from the disease. While it isn’t in Montana yet, wildlife biologists continue to monitor for its presence because it will have a significant effect on our state if it arrives. Take the time to learn about these unique and essential creatures and discover ways to live in harmony. For more information regarding vertebrate pest control, stop by MSU Extension in Broadwater County at 416 Broadway in Townsend or contact 406-266-9242 or allison.kosto@montana.edu.
