Fact Sheet 791

Got Bugs? Get !

Introduction Illustration Illustration courtesy of Angie Franco. Bats are one of Maryland’s most valuable natural resources. However, they are also Finally, bats do not fly into women’s hair one of the most misunderstood and falsely and actually tr y to avoid human contact. accused of all creatures in the king- Many people are war y of bats because of dom. Movies often portray bats as blood- their looks and erratic flight. Bats navigate sucking, rabies-infested, vicious creatures by echolocation, which is a means of bounc - that like to fly into women’s hair. But con- ing sounds off of objects to determine their trary to popular folklore, all the size and location. In most cases, if a bat flies found in Maryland eat only insects. They near you, it is pursuing an insect that is fly - do not suck blood and their rate of rabies is ing close by. considered to be half of one percent in the Bats may not be considered one of the wild. Many more people die each year from most attractive creatures in the animal king - bee stings or dog attacks than from rabies dom but they are an integral part of the food contracted from a bat. Needless to say, the chain and also provide benefits to humans. public health threat from bats has been over- This fact sheet will describe the important estimated. Even so, bats are wild and role bats play in controlling insects and will will bite when handled, so it is recommend- provide information that can be used to ed not to pick up bats whether alive or dead. attract bats to your area. Instructions for removing bats from inside your house are tures is to construct multiple bat houses in also included. either a different design or with a different exterior color. Darker exterior colors will keep more heat in the box, which may be How Do Bats Help People? beneficial during the cooler spring months. Bats are the primary consumer of night- But during the hot summer months, a dark time flying insects. They eat hundreds of exterior may increase the risk of the bats different insect pests, including mosquitoes. overheating and abandoning the roost. For Many of the pests that the agricultural com- this reason, a lighter colored bat house situ- munity and general public try to control ated adjacent to the darker house may pro- with insecticides are eaten by bats. The vide the needed difference in temperatures. insect eating capabilities of bats are quite Also, ventilation slits can be incorporated significant. One little brown bat, which into the design to help prevent boxes from is a species common to Maryland, can eat getting too hot in the summer. approximately 1,200 mosquito-size insects per hour. A typical colony of 150 House Specifics bats, also found in Maryland, can protect local farmers from the costly attacks of 33 Sun exposure: The amount of expo- million root worms each summer. Other sure to the sun a bat house receives is more insect pests on the bat’s menu include important in areas north of Maryland cucumber and June beetles, stink bugs, and less important south of Maryland. In leafhoppers, cutworm and corn ear worm Maryland, bat houses should receive at least moths. There are many other insect species 5 to 7 hours of direct sunlight. As noted not listed here that bats eat every night dur- earlier, providing two houses back to back, ing the warmer months of the year. one light brown and one dark brown should provide the bats with a greater range of tem- peratures to chose from throughout the day. How to Provide If the bats get too hot or too cold during the day, they will often crawl into the other Habitat for Bats house to help regulate their temperature. The habitat requirements for bats are fairly In Western Maryland, bat houses should be simple, but attracting bats isn’t always easy. almost black. They are one of the most finicky of creatures Height above the ground: Studies indi- when it comes to their shelter requirements. cate the higher the bat house, the more Bats may occupy human-constructed hous- likely it is to be inhabited. Occupancy rates ing if it is properly built and placed in a suit- will most likely be highest in houses situ- able area. ated at a minimum height of 12 feet, but 15 Of the 10 species of bats found in feet or higher is recommended. The base Maryland, five are most likely to inhabit of the posts or poles should have a predator houses built by humans. These five species baffle attached to prevent predators such as are the little brown bat (Myotis lucifugus), cats and raccoons from raiding the house. big brown bat (Eptisicus fuscus), the evening Aluminum flashing wrapped around the bat (Nycticeius humeralis), Northern long- poles at a height of 4 feet above the ground eared bat (Myotis septentrionalis), and Eastern will serve as an effective baffle. Bat houses Pipistrelle ( subflavus). The other may be mounted on houses or barns only if species that normally do not use bat houses the bat house will receive a minimum of 5 are the Indiana bat, small-footed bat, silver- hours of direct sunlight. haired bat, red bat, and . Size: The larger the bat house, the greater The temperature inside the bat house is the number of bats may fit. A house with one of the most critical elements in attract- the dimensions 36”H x 24”W x 10”D will ing bats. Providing a variety of different accommodate approximately 300 bats. temperature ranges for bats can be effective Larger houses are also more effective in in attracting and keeping a colony of bats. providing the space necessary for breeding One way to maintain a variety of tempera- females and their pups. Many of the small

2 bat houses available on the market are inef- recommendations, bat proofing your house fective and not often used by bats. The should be done after September 1 and before plans for two different size bat houses are hibernation begins, which is normally in included in this fact sheet (refer to appendix). November. Bat proofing should not be done Proximity to Water: Bat houses located during the late spring and summer months. one-quarter of a mile from a stream, river, During the summer, bat pups are dependent lake, or pond are more likely to attract bats. upon their mothers for milk and will not The size of the body of water is not a signifi- leave their roosting area until mid- to late cant factor. July. If a house is bat proofed between May Open area: Bat houses erected in open, 1 and August 31, the likelihood of trapping a nonforested areas are more likely to attract bat pup in your house increases. This should bats. Bats prefer to have few flight obstacles, be avoided because the pup will most likely and for this reason open areas are suggested die and decay causing bad odors. Also, the over forested areas. Bat houses can also mothers may try to get to their pups, which be mounted on the side of a barn or other could lead to them finding another way into structure if it is at the proper height and your house. receives 5 to 7 hours of direct sunlight. Exclusion during winter should also be avoided because certain species may hiber- • The success of bats occupying bat houses depends on nate in houses. Big brown bats have been bat populations in the area, the suitability of present roosts, and the diversity of habitat types, which pro- known to hibernate in houses and even in vides more food sources. Maryland bats historically properly constructed and located bat houses. occupied dead and dying trees in the landscape, Unless you are absolutely sure there are many of which have been removed, which is the not any hibernating bats in your home, it reason bats have switched to human houses in the is advised not to exclude during winter to first place. The amount of displacement from their roosts also influences the success of bat boxes. avoid trapping hibernating bats inside. Prior to excluding bats from a house, it is recommended to provide the bats with an Are Bats in Your House? alternate roosting site. This may be accom- plished by erecting a bat house, like the ones The Facts on Excluding Bats produced by following the guidelines provided Under the Maryland Nongame and in this fact sheet. The first step in excluding Endangered Species Conservation Act, bats bats from a house is to determine where they receive protection. It is against the law are gaining access. Once the access point has to “take” any bat, which means to harass, been identified, exclusion can begin. harm, pursue, hunt, shoot, wound, kill, trap, One-way devices constructed from light- 1 capture, or collect, or to attempt to engage weight polypropylene netting (< ⁄6” mesh), in this conduct. For this reason, it is impor- plastic sheeting, or tube-type excluders are tant to learn how to properly manage any the preferred methods for evicting bats from bats that may be roosting in your house. buildings (please refer to the illustration on page 4). Excluders should be placed at all When Should I Bat Proof My House? active entry points and should remain in place for at least 5 to 7 days. These devices • It is important to note that in Maryland, only bat should be removed after the bats have been exclusion professionals with a permit from the excluded, and then exclusion points should Department of Natural Resources are allowed to do be sealed with silicone caulking, caulk back- bat exclusion work. A list of these businesses and ing rod, hardware cloth, or heavy duty poly- individuals is available by contacting the Maryland propylene mesh. In some cases, sealing may Department of Natural Resources (DNR). require repair or replacement of old, deterio- Just like any other wild animal, bats do rated wood. It is recommended that exclu- not belong inside peoples’ houses. If bats are sion professionals bat-proof the entire house occupying the eaves or another location in and avoid spot treatments. Moving bats from your house, it is best to exclude them from one corner of a building to another does the house. According to Maryland DNR not solve the problem and may require that

3 and discourage them from gaining access to your house by following the guidelines out- lined above. References Maryland Department of Natural Resources. Bats of Maryland. Annapolis: Wildlife and Heritage Division. Tuttle, M., and Hensley, D. 1993. The Bat House Builder’s Handbook. Austin: Bat Conservation International. Williams, K. and Mies, R. 1996. Understanding Bats. Marietta: Bird Watcher’s Digest Press. Williams-Whitmer, L., and Brittingham, M. 1995. A Homeowner’s Guide to Northeastern Bats and Bat Problems. University Park: Penn State College of Agricultural Sciences, Cooperative Extension. Illustration Illustration courtesy of Angie Franco. more exclusion work is carried out at some Additional Resources time in the future, further disturbing the Maryland Department of Natural Resources bats and the property owner. Wildlife Hotline Number (877) 463-6497 • Please note that simply waiting until the bats have flown out at night and then permanently sealing Bat Conservation International, Inc. entrances shut without the use of exclusion devices, P.O. Box 162603 is not recommended. This method often traps bats inside the building. Austin, TX 78716-2603 (512) 327-9721 Finally, if you have a colony of bats roost- www.batcon.org ing in your house or another building, it is beneficial, for you and the bats, to provide Organization for Bat Conservation them with an alternative roost site and then 1553 Haslett Road exclude them from the unwanted location. Haslett, MI 48840 Bats are very effective in naturally suppress- (517) 339-5200 ing insect pest populations. Encourage bats www.batconservation.org to live in your area by erecting bat houses

APPENDIX The following bat house plans were reproduced with permission from Woodcrafting for Wildlife by the Pennsylvania Game Commission.

4 Small Bat House

5 Standard Bat House

6 Standard Bat House Continued

7 Got Bugs? Get Bats! by M. Allan Daly Extension Educator Baltimore County

Reviewed by: Elijah Goodwin Dana Limpert Organismic and Evolutionary Biology Ecologist University of Massachusetts Maryland Department of Natural Resources

Jonathan Kays Robert Tjaden Regional Specialist, Natural Resources Regional Specialist, Natural Resources Maryland Cooperative Extension Maryland Cooperative Extension

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, University of Maryland, College Park, and local governments. Bruce Gardner, Interim Director of Maryland Cooperative Extension, University of Maryland. The University of Maryland is equal opportunity. The University’s policies, programs, and activities are in conformance with pertinent Federal and State laws and regulations on nondiscrimination regarding race, color, religion, age, national origin, gender, sexual orientation, marital or parental status, or disability. Inquiries regarding compliance with Title VI of the Civil Rights Act of 1964, as amended; Title IX of the Educational Amendments; Section 504 of the Rehabilitation Act of 1973; and the Americans With Disabilities Act of 1990; or related legal requirements should be directed to the Director of Human Resources Management, Office of the Dean, College of Agriculture and Natural Resources, Symons Hall, College Park, MD 20742.

R2004