Bat Little Brown

Binomial Name: Myotis lucifugus


  • Forearm: 3.4-4.1cm
  • Wingspan: 22.9-26.9cm
  • Ears: 1.4-1.6cm
  • Colour: Reddish brown to dark brown

Life Cycle: In Southern Ontario litter size is one, however, twins occasional occur in warmer regions. In captivity the life span of the little brown bat can be as great as 31 years. In the wild life expectancy is limited to only a few years.

Behaviour: The little brown bat is one of the most common bats found in and around buildings. Being able to tolerate high temperatures,summer colonies often roost in hot attics. Colony size can range from approximately a dozen to thousands. In the winter little brown bats will leave their summer roost sites to hibernate in caves. Their winter roost sites may be up to a few hundred kilometres away from their summer roost sites.

Signs of Infestation: If you believe that you have little brown bats roosting in your home you can verify your suspicions with a “bat watch” (look for bats flying in and out of your home). To perform a bat watch, observe the exterior of your home in the evening about 30 minutes before dark. Multiple people may be needed to cover all exterior surfaces. Little brown bats only need a 1/4” opening to gain access into your home so pay attention to even the smallest of openings. It may be necessary to perform multiple watches to compensate for weather conditions, bat’s sensitivity to observers, noisy or inexperienced observers and improper use of lights.