Bats Are Beneficial Mammals
Katie Tomlinson, Master Gardener

August 7 , 2002

Bats can provide terrific nighttime entertainment. Try going outside on a summer evening an hour or so after sunset with a tall drink to relax. After sitting quietly for a short while, your eye will start to catch small black patches flitting around in what appears to be a mad dash. That bat your eye just caught a glimpse of will go on to consume one-fourth its own weight of insects in just one night. Bats are unique because they are the only mammals that can truly fly and they have a highly developed echolocation sensory system that allows them to locate flying insects at night. Bats are beneficial because of the insect consuming role they play in the ecosystem.

There are many species of bats in New York, both colonial and solitary. Colonial bats called little brown bat and big brown bat are the species most apparent and most closely associated with problems homeowners may have. One little brown bat can catch more than 1,200 mosquitoes-sized insects in one hour. This is good, but the problem starts when a colony of bats takes up residency in your home. A roost could be as small as a dozen or as large as several hundred bats. These two species have adapted nicely to human-made structures, possibly making their colony size larger then what might naturally occur. Noise, odors and stains are the issues homeowners have to contend with. The noises come from the bats vocalization and activities and the odors and stains from urine, feces and rejected food. There are some health risks involved with bats being present in your home or outbuildings. Histoplasmosis fungus can be contracted in humans by breathing airborne spores in the dust of bat manure and bats carry parasites including mites, ticks and fleas. Bats are carriers of rabies and may not show signs of the disease as exhibited in other mammals. However, if they are seen during the day or laying in a weakened state, they are probably suffering from rabies and should be left alone. Bats are not aggressive, but if they are handled they will bite. Should a bite or scratch occur, wash the infected area with soap and water, capture the bat without hurting its skull for analysis and contact your local Public Health Office.

A long-term and acceptable way to control bats around your home is to bat proof the house or building the colony resides in. All points of entry must be sealed off. But before this can be done, some thought needs to be given to the bat's culture. In New York, little brown bats' young are airborne by August 1 and big brown bats' young are airborne by July 7. Anytime after these dates would be preferable in order to minimize odors from decaying carcasses. If there is more then one opening, seal all but one of the openings. Leave the one opening for three days. Then a half an hour after dark on the third day when all the bats have gone on a feeding flight, close off the last opening. Most any building material will work. If possible, after exclusion, an attempt to remove dead carcasses and excrement should be made wearing protective clothing and a respirator. If not removed the materials will attract other insects or even more bats. In outbuildings that aren't able to be sealed, low-watt lighting or increased ventilation may deter colonies from moving in. Mothballs may be useful in low ventilation areas.

Overall, bats are enormously beneficial and should not be killed unless absolutely necessary. Cornell recommends exclusion or repelling as the most practical way of controlling bats. Master Gardeners invite you to call and share your gardeneing experiences with them at 315.536.5123. Past articles written by Cornell Cooperative Extension Yates County Master Gardeners can be found at www.cce.cornell.edu/yates/index.htm.

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Cornell Cooperative Extension Yates Association
Last updated: 8/7/02

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