:^ 



United States Department of Agriculture 



Bureau of Biological Survey -■ '^ - 



AY3-I93t 



Wildlife Research and Management Leaflet BS^7 .Mtment of Ae?-ior 



Washington, D. C. * - ^ April 1935 



I NSTRUCTIONS FOR CONTROLLING BATS 



Prepared in the Section of Predator and Rodent Control 

 Division of Game Management 



Bats are almost entirely beneficial, but complaints against them are 

 made largely because of the results of their roosting in homes and other oc- 

 cupied buildings. The objection to their presence is due in part also to an 

 aversion that many people have to them, just as they have to snakes, spiders, 

 and rats, but more because of the highly objectionable odor that is always 

 associated with a roost of bats. This pungent, penetrating odor comes from 

 their droppings and urine, which collect rapidly under their roosts and make 

 it necessary to drive them away, to shut them out, or, as a last resort, to 

 kill them. The following control methods are suggested; 



It is frequently possible, by the use of naphthalene, to drive bats from 

 their congregating places in attics, double walls, or other enclosed spaces that 

 afford suitable roosting sites. The naphthalene can be purchased at local drug 

 stores either in the flake form or as common "moth balls." The flakes, which 

 are preferable for this purpose, should be thrown liberally around the places 

 occupied. Usually 2 to 5 pounds are required to drive the bats from the average 

 roost in a building. The treatment should be repeated after a week if neces- 

 sary. The odor of the naphthalene is so objectionable to bats that usually 

 they will leave the premises where it is used. 



Bats can sometimes be shut out of an established roost in a building, 

 though this is often difficult, as there are usually many openings through 

 which they can gain entrance. They can be excluded, however, by finding and 

 closing all the openings they use. In blocking such openings, at least one 

 should be left open until after dark, when the bats leave on their nightly 

 search for food. After all the bats are out, the remaining openings should be 

 closed. 



Fumigation with calcium cyanide has been effective in destroying the 

 roosts by killing the bats. The gas generated, however, is so deadly that ex- 

 treme care must be used to avoid endangering human life. The odors created by 

 the bats thus killed also are objectionable. Calcium cyanide in dust or granu- 

 lar form should be inserted into the cavities occupied by the bats. Because of 

 the danger of using the cyanide, however, this method should not be employed 

 when the use of naphthalene as a repellent will answer the purpose or when the 

 bats can be shut out of a building as above described. 



