Bats
Overview
Bats are nocturnal, flying mammals which like to live in dark, secluded areas. They have been falsely associated with witchcraft, sorcery, haunted houses, cemetaries and evil in general. Over the years they have been the subject of fables, folklore and myths, unfortunetely these myths still exist today and serve as a basis for unfounded fear. They are a medical concern as thier old droppings, or guano, may harbor a fungal organism that causes the lung disease Histoplasmosis, also a very small percentage of bats are infected with rabies.
Facts
- Bats are flying mammals, not birds. The mother has has one baby called a pup and feeds them milk. They are not born from eggs like birds. The pup will stay with the mother for one year.
- There are no Vampire bats in Minnesota.
- There are only two species that invade homes in our area: Large Brown Bats and Little Brown Bats.
- One little brown bat can eat more than 600 mosquitoes in a single hour.
- Bat droppings can carry several diseases such as histoplasmosis. Great care should be taken prior to cleaning up droppings as the dust like particles can get airborne easily, breathed into your lungs, and spread disease.
- They have a “functional” eye and are nor blind, but rely on their “sonar” to navigate during flight.
- Bats are very clean animals. They clean themselves and each other meticulously by licking and scratching for hours.
- Bats, when at rest, cannot just “fly” like a bird. They must first go through a “warm-up” period, in which they stretch in an effort to get the blood flowing to the muscles in their wings.
Identification
- Large Brown Bats are relatively large - about 4 inches in length and having a wing span of 12-14 inches.
- Large Browns weigh about 1/2 ounce.
- Little Brown Bats are about 3 inches in length, weighing about 1/4 ounce.
- It is difficult for most to tell the difference between the two. Treatment procedures are the same.
Biology
They mate in the fall, and the young are born in June - July (usually only 1 per year).
Habits
- They are most active at night, feeding on flying insects, up to 1,500 insects per bat per night.
- Will eat “moth” sized insects.
- Seek out protected areas (overhangs, soffits, above doors, etc.) to “rest/eat/digest” during the night. Homeowner may see droppings below these areas.
- Large Brown Bats will hibernate for the winter whereas Little Brown Bats will migrate.
- Large Brown Bats will generally hibernate in a different location than where they “roost” during the summer.
- They will hibernate under attic insulation and down in wall voids, periodically waking, moving about, sometimes entering the living areas of homes.
Treatment
It is illegal to use any pesticide against bats!
We recommend sealing up the building to exclude the bats and provide for the best long term solution. Inspection should always be performed first to determine:
- Is there evidence of bats?
- If so, how big is the pressure (how bad is it)?
- Identify how many bats there are. Where are the openings?
- Are the obstacles to sealing the structure?
- Any health hazards/health risks, due to bat droppings?
- Can the structure be bat-proofed safely?
Exclusion materials may include: ¼ in mesh screening, Silicone caulk, Duct Seal (like putty), Small pieces of wood, etc.
Be wary of any quote to perform structural repairs over the phone as the price will either be too low to perform the job or too high to cover worst case scenarios.
Bat exclusions are non-trivial and rarely performed well by those without carpentry and pest control backgrounds. Some of our customers before hiring us have paid over $10,000 to re-roof their house, only to have the bats return within a year. Make sure you hire a pest management firm like Adam's who knows bats and who knows construction. Also, make sure the company you hire is licensed, insured.
We recommend you hire Adam's to send out a Bat Exclusion Specialist and perform an inspection, provide consultation, provide further education, and a no-obligation estimate for sealing up your home. Should you accept our exclusion estimate, we'll seal up most of the holes, leaving one or two “open” to allow bats to exit and feed at night (which they must do). Over these few open holes we install a one way device which allows the bats to leave…but not re-enter. Best of all, we warrantee our work for two years! We'll then return in about two weeks to seal the remaining holes. We do not spray moth balls, flakes, repellents, pesticides, nor disinfectants!
Frequently Asked Questions
Q: Do bats have rabies?
A: The rabies virus kills the bats, so they are rarely carriers of the disease. Do not approach bats that are on the ground, unable to fly, as they may be dying from the disease and would be a high risk if you handled it.
Q: Bats loose in the house?
A: Try to isolate the bat in one room, put towels or a rug under the door. If it’s summer, open a window the bat should leave. If it’s daytime and the bat has been at rest, you should be able to walk up to it and put a coffee can over it so that you can trap it inside and remove it from the house. Remember, if it is at rest it cannot just jump and fly, it needs to warm-up first.
Q: Bats loose in house in winter?
A: Bats hibernate during winter, so they are not active like they would be in the summer. There is no food for the bats in the winter as they eat flying insects. More than likely, they have been “woken” from their hibernation and crawled around and somehow found themselves inside the house. You have to trap and remove the bat. Bats making it inside during the winter is usually an indication a colony exists within your walls or attic.
Q: Scratching noise in walls/ceiling?
A: If the noise is restricted to one area and it doesn’t sound “heavy” or is not “scampering” it likely is a hibernating bat. When bats hibernate they will go under the insulation or down into wall voids where they feel safe and protected. This is much different than during the summer when they “roost” along the rafters of the roof. They periodically will “wake up” from their hibernation and move around a bit. This is what you hear and it generally occurs during temperature “spikes.” There is nothing that can do for this, until they become active enough to feed at night. Have a professional inspect in the Spring.
Q: Bat droppings on sidewalk/steps, etc.?
A: This is a result of the bats taking a break during the night in which they will rest, eat a captured insect, and digest their food. There is not much that can be done except to screen the area (generally an overhang, portico or soffit), to prevent bats from temporarily roosting in those areas.

