Bat behaviour
Bats are flying mammals that serve a very useful purpose: they eat enormous quantities of insects. In the summer, they can find their way into homes—typically in roof eaves, in crevices around the roof covering, in the attic, or under siding—where they roost in large groups called colonies. They can enter through an opening as small as 6 mm wide. Bats usually settle near a body of water (e.g., pond, lake, marsh, swimming pool).
Do not let them take up residence anywhere in your home—not even in the attic. The presence of bats, their feces (commonly referred to as guano) and urine, as well as the parasites they carry, will result in unsanitary conditions.
A further concern is rabies transmission: a very rare occurrence, but still a possibility. In the evening or at night, when bats are active, one or two may involuntarily find themselves inside your house. If this happens, they must be got rid of.
Are bats useful or bothersome?
Useful
- A single bat can devour thousands of mosquitoes and other insects in one hour.
Their activity allows for reduced use of insecticides in farming areas and, in turn, less ground and water pollution.
Bats are natural eliminators of stinging and biting insects that are recognized carriers of diseases like West Nile virus, Lyme Disease, etc.
Bothersome
- Bats can transmit rabies by biting or scratching. A bat’s teeth are so tiny and sharp that you could be bitten and not even notice it.
Large groups of bats can be noisy.
Bat feces (guano) gives off an obnoxious odour and can contain a fungus called Histoplasma capsulatum, also found in the droppings of several bird species, including pigeons. If guano dries and becomes powdery, it must not be stirred up, because breathing in the dust can cause histoplasmosis. This lung condition develops only rarely, but there is a risk of complications. Note that the fungus does not usually survive in hot, dry attics.
Bats can carry bat bugs, which are similar to bed bugs and can infest the home.
Tips for keeping bats away from your home
1. If a single bat is loose in your house:
Before you begin, put on a pair of leather work gloves.
Open doors and windows and wait for the bat to fly out on its own. If the bat is there in the daytime, leave all indoor lights off; the bat will leave when night falls.
If this doesn’t work, try to capture the bat and release it outside. You can use a net (e.g., a dip net used for fishing) or trap it against a wall using a container, sliding a piece of cardboard underneath to temporarily imprison it.
Good to know
If you find a dead bat on the ground, pick it up with a shovel, dump it into a container, and send it for autopsy. To arrange for this, contact the Canadian Food Inspection Agency (CFIA).
2. To keep bats from entering the house:
Spring (before they arrive) and fall (after they leave) are the best times of year to block holes that can serve as entry points for bats—provided, of course, that you can locate them. To find out where they are getting in, and prevent them from returning:
Wait until after dark and watch the bats as they fly into and out of the house; you should be able to locate the entry/exit points.
Attach bird netting (fine-mesh) over the entry points you’ve identified, leaving the bottom part hanging loosely so that the bats can exit the roost site but won’t be able to get back in.
Wait a few days until you no longer see bats leaving or attempting to return, then remove the netting and seal the openings.
Note that in the case of a full-blown colony, you’ll need to call in a pest control specialist.
See our tips on how to choose an exterminator wisely.
How to clean up bat feces (guano)?
Here again, if you need to clean premises that have been infested by guano, you must rely on a pest control specialist or structure decontamination expert.
These contractors should first seal any opening or crack between the attic and the lived-in areas of your house, to reduce the risk of contamination.
If you find droppings left by a single bat that was in your home briefly, you can clean them up yourself. Wear gloves and a protective mask, and moisten the affected surface before cleaning it with soap and water.
To learn more about bats
HEALTH CANADA
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