How to Get Rid of Bats – An Integrated Pest Management Bat Action Plan
Bats are a highly beneficial wild animal. However, they come into conflict with humans when they create their nests in our homes and other structures. Literature and ancient lore often portray bats as dark, evil, blood sucking monsters. “Blind as a bat” is an acceptable phrase in our society, yet bats are not blind. In fact, they have very small eyes that enable them to see in very dark surroundings. They also use sound waves (echolocation) to help them navigate and locate food.
There are more than 40 species of bats in the United States. Most bats eat only insects, but a few species eat nectar and fruit. Vampire bats feed exclusively on the blood of other animals. Currently, vampire bats are not found within the United States. However, the range of the vampire bat is expanding north from Mexico, and it is expected to be found in Lower Rio Grande Valley of Texas soon.
Bats live in a variety of places including caves, abandoned mines, hollow trees, under tree bark, in palm fronds and in crevices under bridges. Bats roost in human structures as more and more of their natural roosts are being destroyed. For this reason, bats are declining, and great care should be taken when removing them from buildings. Consider adding a bat box as a replacement roost site.
Getting rid of bats roosting in your attic or shed requires some general bat knowledge, specialized equipment, and a healthy dose of fortitude. Most professional wildlife trappers are knowledgeable and experienced in the safe removal of bats and the laws specific to bat removal in your area.
Bats provide an important ecological benefit; they eat tons of insects. Bats are the most effective natural or organic pest control available. Some bat species eat their weight in insects every single night! Scientists estimate that bats eat enough insects to save billions of dollars in pest control services every year. Bats eat insects that damage many agricultural crops such as corn, sugarcane, tomatoes, cucumbers, beans, cotton, pecans, and almonds.
Some bat species are also important pollinators. In contrast to the brightly colored daytime flowers that bees pollinate, bats tend to pollinate nighttime blooming flowers that are pale in color. Some species of mango, banana, guava, and agave, which is used to make tequila, are pollinated by bats.
Despite their obvious benefits, when bats roost in our homes and businesses, we must evict the bats. Bats are vectors of diseases that can harm people and pets. Bats can transmit rabies by biting. Within the general bat population, the rabies infection rate is only 0.5%. However, if you encounter a bat on the ground or on the floor, there is a 33% chance that bat is infected with rabies. Some rabid bats appear disoriented or clumsy in their flight, they may become aggressive, and they may lose their ability to fly altogether. These are the bats that are more likely to mistakenly end up inside your home, porch, or garage. You should not handle a bat that exhibits any of these symptoms. People that frequently handle bats should consider having pre-exposure rabies prophylaxis.
When bats establish roosts in our homes of businesses, they bring with them a number of issues. Bats can carry with them other insects that can infest your home. Bat mites, also known as, bat bugs are similar to bed bugs except they prefer to feed on the blood of bats. If bats have brought these insects into your attic, you may experience bites when you get rid of the bats. After the bats are removed from the attic, bat bugs may venture into the living areas of your home in search of a blood meal. Bat bug infestations are a rare but severe consequence of bats roosting in your attic. Because bat bugs look and feel so similar to bed bugs, they are often confused for one another. If you are dealing with a “bed bug” infestation that simply will not go away, make sure your Pest Management Professional knows that you had a previous bat infestation.
Bat guano or bat droppings are a serious health risk on a few fronts. As noted above, some bat species eat their weight in insects nightly, but this generates a lot of bat droppings. In confined spaces such as an attic, bat guano smells awful. When bat guano is present, indoor air quality is diminished and allergens increase. Histoplasmosis is a serious disease that is caused by inhaling infected bat guano. When a bat is infected with histoplasmosis, its fecal matter contains histoplasma capsulatum fungus. As this guano dries out the fungal spores become airborne. When breathed, these spores can cause histoplasmosis, a potentially serious respiratory disease.
Bats are found all over the world, with the exception of the Arctic, Antarctica, and a few small islands. Bats can live in almost every habitat including, forests, deserts, big cities, and suburban neighborhoods. They live and roost in a variety of structures. Every species of bat has its preferred nesting location, but common ones are caves, trees, rock crevices, old buildings, and bridges. When temperatures turn cooler, and the abundance of bugs diminishes, some species of bats hibernate, and some species of bats migrate.
Bats sometimes decide to roost in your home. Bats will not chew through building materials to create openings, but they will certainly exploit and utilize any opening that they find. A hole or opening in a wall or attic ¾” or more is large enough for bats to enter. In cases of severe bat infestations, the entry hole is often larger than ¾ of an inch.
There are approximately 45 species of bats currently in the United States. Each species is biologically unique and has different characteristics and preferences. Bat identification is important as some bats are federally protected under the Endangered Species Act. In addition, bat identification is important so that you are aware of the bat maternity season for the particular bat at issue. By excluding bats during this time, you will trap the bat babies in your attic. This is often illegal and it will cause you further attic issues in the future.
- Colony Size – Large colonies, up to 300,000 bats
- Physical Characteristics – Small, between 5 – 14 grams, usually dark brown, small ears, wings are nearly hairless
- Food – Insects
- Winter Survival – Migrates short distances, and hibernates
- Geographic Range – Across much of North America, but not found in Florida
- Colony Size – Females create nursery colonies to rear the young, usually between 20 – 300 animals per colony
- Physical Characteristics – Large bat with copper colored fur, small round black ears, weighs between 15 – 26 grams
- Food – Insects
- Winter Survival – Hibernation
- Geographic Range – Across much of North America, Central America, and the northern part of South America
- Colony Size – Varies
- Summer – females roost together to rear their young, usually less than 100 adults
- Winter – males and females hibernate together in caves by the thousands
- Physical Characteristics – Small size, average 7 grams in weight, dark grey or brown in color with soft fur
- Food – Insects
- Winter Survival – Hibernate and Migrate
- Geographic Range – Only found in North America, spans from the Midwest to New England states
- Colony Size – Ranges from 12 – 100 bats
- Physical Characteristics – Medium size (17 – 28 grams), pale cream-colored wooly fur, can produce a skunk like odor
- Food – Insects, unlike other bats, pallid bats drop low to the ground to catch insects
- Winter Survival – Hibernate
- Geographic Range – Western North America from British Columbia to Mexico – partial to desert habitats
- Colony Size – usually roost alone in trees
- Physical Characteristics – Dark brown fur with white tips giving it a “frosty” appearance, yellow patch on the throat, between 20 – 35 grams, blunt round nose and small eyes
- Food – Insects, primarily moths
- Winter Survival – Migration
- Geographic Range – Much of North and South America, the most widespread bat in the United States
- Colony Size – Solitary, except to mate and migrate
- Physical Characteristics – Brick or rusty red in color with a patch of white fur on the shoulder, medium size bat weighing between 7 – 13 grams
- Food – Insects, primarily moths
- Winter Survival – Migrate and Hibernate
- Geographic Range – Primarily east of the Continental Divide from Canada to Mexico
- Colony Size – Large colonies, hundreds to thousands
- Physical Characteristics – Medium size bat, average 7 – 12 grams, long, narrow, and pointed wings, tail extends beyond its body
- Food – Insects
- Winter Survival – Migration
- Geographic Range – Widely distributed in North America, Central America, and South America
- Colony Size – Small, fewer than 100
- Physical Characteristics – Dark brown except for its black ears. Snout, wings, and tail membranes are hairless, between 6 – 14 grams
- Food – Insects, specifically the chrysomelid beetle. The larva of this beetle is known as corn rootworm, which damages corn crops.
- Winter Survival – Females migrate, males remain in the southern portions of the geographic range all year
- Geographic Range – Midwestern and Eastern United States, as far south as Florida
- Colony Size – Large colonies, usually between 2,000 – 90,000 bats per colony
- Physical Characteristics – Thick wooly fur that is darker at the base and whitish at the tips, live mostly in caves, unusually long toe hairs, usually weigh between 5 – 8 grams.
- Food – Insects
- Winter Survival – Northern populations hibernate, but Florida populations remain active
- Geographic Range – Southeastern United States, predominantly in Florida
Many species of bats are protected by state and federal laws. Bats are vulnerable due to loss of habitat and disease such as White Noise Syndrome. At this time, The Endangered Species Act protects 6 species of bats. However, state and local governments may have more stringent protections and rules regarding bats. Before you undertake any bat removal attempt, be sure to know the rules and regulations in your state and local municipality.
It is important to follow all laws to protect these beneficial animals. What is allowed in one state, may not be allowed in another. For example, some states strictly prohibit bat exclusions during the maternity season. Other states permit only licensed professionals, not homeowners, to exclude bats during this season.
If possible, identify the species before attempting to remove bats from a building. Some bats are easy to identify but others require training and the use of identification keys. Knowing the bat species will help in managing bats; some species of bats are migratory and will leave the premises. Other species of bats hibernate in the winter and will not leave. Ask someone from the state wildlife agency or Bat Conservation International to determine which species of bats live in your area.
Bats are not flying rodents; they belong to a unique order of mammals called Chiroptera (Latin for “hand wing”). Because bats are mammals, they give birth to live young. The life cycle and mating habits of each species of bat is different, but in there are similarities.
- Most bats mate in the fall. Females hold the semen in a special gland until the winter is over.
- Once she awakes from hibernation, she ovulates and uses the stored sperm to fertilize her eggs.
- Pups are generally born in the spring or early summer (mid-April to June).
- By late summer, the pups are able to fly and feed on their own.
- Most species produce one pup a year, although a few species give birth to litters of two to four pups.
In general, bats are caring and attentive mothers. Bat pups can weigh up to 1/3 of their mother’s weight when they are born, but they require months of care and feeding before they can be independent. Some female species of bats form nurseries where they communally care for their young. This allows some female bats to remain with the young and other females to go out and hunt for food. In these large nursery communities, mothers and babies recognize and find each other, perhaps using echolocation, smell, or by unique chirps.
It takes a few months for the pups to be able leave the roost. If a bat exclusion is performed during the time that they are dependent upon their mothers, they will not survive.
If you suspect wildlife to be living in your attic or a wall void, you must thoroughly inspect the area. Maybe you hear the chirping of a bat nursery. Maybe an overwhelming odor is emanating from the area. Perhaps you’ve even watched at dusk as bats evacuate from your attic. Bat inspections should involve all the senses.
- Visual inspection for bats entering and exiting building, as well as the presence of guano (bat droppings).
- Guano can be seen but also has a pungent odor that is often a clear sign that there is a problem.
- Bats may also be heard in large populations, at dusk as they prepare to fly you may hear high pitched chirping sounds.
The first step in bat management is to find bat entry points in and around buildings. Inspections should be conducted 1/2 hour before sunset or sunrise and look for bats entering or exiting the building. Don’t inspect during rain, strong winds or temperatures less than 50°F. During cooler months, inspection may need to be repeated several nights in a row to establish exit and entry points because bats do not leave the roost at night if temperatures are too cold. Inspection is extremely important in identifying where to place bat eviction doors, tubes, or nets.
Bats normally enter near the top of structures. Unlike rodents, bats are not generally capable of chewing openings and must use existing holes. An opening the size of your thumb (3/4”) is enough for a small bat to squeeze through, but buildings with well-established roosts will probably have larger openings.
During an initial inspection, it should be determined whether any person or pet has been bitten or otherwise had direct contact with a bat. If this has occurred, the local health department should be contacted, and the bat should be tested for rabies if the specimen is available.
If possible, species identification should be done to aid in determining colony roosting behavior. If the species is known to roost in large numbers, colonies can have multiple access points into a structure, which makes eviction harder.
Bats are creatures of habit and will return to the same roost year after year. Often during cool weather, if bats are roosting inside a structure, they will move farther into the structure to stay warm. Depending upon the species, bat colonies can expand from a few hundred to several thousand. There are no chemical control options for bats. All methods require patience and understanding of bat biology and total eviction and exclusion. For large bat colonies, hiring a professional bat excluder is recommended because bat exclusion work requires the ability to work and stay on tall ladders for long hours.
Exclusion is the best way to remove bats and keep them from coming back. This often involves sealing bat entry points and installing check valve device or a one-way door. These devices allow the bats to leave, but they can not get back in. Recognizing the benefits of bats to their yard, some people choose to build a bat house nearby. This gives the evicted bats a place to roost that doesn’t damage your home while retaining the pest control benefits of bats in the neighborhood. Be sure to check local ordinance and deed restrictions before installing a bat house.
Seal Bat Entry Points. Often, spot repairs with simple materials will be sufficient. In some cases, part of the structure (such as the roof) may need to be rebuilt. You can prevent bats from entering the human living space of a building by sealing all openings. Any opening in the walls or roof larger than ¾ inch can allow bats to enter the structure.
Common places for bats to enter homes include:
- Gaps under and over attic doors
- Gaps around pipes passing into the ceiling
- Pocket doors that slide into walls
- Loose fitting baseboards and broken plaster
Colonies of bats may be effectively evicted from a building using check valves. Check valves operate like a one way door for bats. When properly installed, bats can leave the roost, but cannot come back in. REMEMBER: All work should be started before the young are born or after they are weaned and able to fly. During eviction, temperatures must remain above 50°F for at least four consecutive days/nights.
Commercial check valves may be purchased, or you can make a check valve out of 2-inch (diameter) PVC pipe, an empty and cleaned caulking tube with both ends cut off, plastic netting, or even clear sheets of plastic.
- Place the tube or netting over the holes in the roof or soffit used by the bats to allow them to leave and block them from reentering the building.
- If bats are roosting in a long horizontal crevice, place a check valve roughly every 6 feet along the entire distance to make sure all bats can get out.
- For some large areas, netting can be used to form a drape to allow bats to exit, but not return.
- If using netting, make sure it has a mesh of less than ¼ inch so bats won’t get caught in it.
- Mesh must not be placed flush against the exit hole as bats will be trapped inside.
- Leave the check valves in place for at least one week during warm weather to make sure all the bats have gotten out.
After the bat eviction device is installed, observe for bat activity. Especially in cooler weather, not every bat leaves the roost every night. A complete and thorough bat exclusion requires that every bat leaves the roost.
Occasionally, bats make it into the living space of your home. Sometimes they gain entry through the chimney, fall down wall voids from the ceiling, or a confused and rabid bat my come in through the open sliding glass door. During removal of bats found within the building, it is important to reduce risk of bites and disease transmission. Removal of individual bats that are found on the floor, or in close proximity to people, needs to be dealt with immediately. Bats that are on the ground are much more likely to be rabid than bats in general.
If you find a bat in or around your home, have the following items available before you approach the bat:
- pair of thick work gloves (to avoid bites)
- plastic face shield
- small cardboard box
- masking or duct tape.
After putting on the gloves and face shield, carefully place the box over the bat. Place a sturdy piece of cardboard under the box, secure the container and tape it shut. Bats should be released ONLY after you make sure no person or pet had direct contact with the bat. After dark take the bat outside and place it on a high surface or close to a tree so the bat can crawl up. Although bats are the only mammal known for its true flight, they generally cannot take off from the ground. They must be 6 feet above the ground to allow enough air movement under their wings for flight.
Once the bats are out of your attic, there is still much work to be done. Bat urine and fecal matter contaminates attic space and the air quality of your home. Remaining bat guano can also attract other pests such as cockroaches or flies. No doubt, bat guano should be cleaned up, but there are risks involved. Any person involved in this job should be healthy and not immune compromised. For an additional fee, most wildlife trappers that do bat exclusion work also do attic clean up and sanitation. Depending on how many bats were roosting in your attic and how long they were there, this can be a particularly awful do it yourself job.
Dried bat guano droppings may contain fungal spores that cause histoplasmosis. Caution should be used when cleaning bat guano in a confined area. Follow CDC guidelines to protect yourself from histoplasmosis by:
- Before removing the bat guano, lightly dampen the deposits by dropping with water and a surfactant (soapy solution) to minimize dust and fungal spore dispersal into the air.
- For large deposits use a high efficacy vacuum with a HEPA filter.
- Identify the appropriate disposal requirements for potentially histoplasmosis-contaminated waste. Requirements vary between counties and states and may be in landfill with prior arrangement or may need to be incinerated.
- Wear appropriate PPE. This should include:
- disposable gloves
- disposable protective clothing (with hood if dust can fall from above)
- shoe covers
- respirator with eye protection that is capable of filtering particles smaller than 2 microns in diameter
- All disposable clothing should be sealed in a bag and disposed along with waste.
After the removal of bat guano consider cleaning the area with an EPA approved disinfectant. These products may reduce odor and kill any remaining bacteria.
Like other mammals, bats can bring in mites, ticks, fleas, batbugs, and/or flies. Depending on the roosting location, a licensed pesticide applicator may also need to make a pest control application after eviction to kill insect and parasites and keep them from entering the living space of the home.