All Minnesota bats are insectivors. They feed exclusively on insects mostly beetles, moths, flies, midges, mayflies, and to a very minor degree, mosquitoes. Biology Bats mate in fall and winter, and the young are born from April through July. An adult female will usually produce only a single newborn each year. Some have twins, and a few species have litters of three or four.
Young bats grow rapidly and are able to fly within three weeks.
Female bats congregate in nursing colonies from the time the young are born until the time they are weaned in July and August. Property Damage Bats may use the interior of buildings as roost sites. These roosts can cause a nuisance when the natural squeaking, scratching, and crawling sounds are heard through walls, ceilings, and chimneys. Bat droppings stain floors and walls and, if enough are present, may cause odor problems. Possible roosting sites in houses.