There are over 40 species of bats that live in North America. The most common in our area are Little Brown Bats. Bats need a safe place to roost during the daytime making attics and chimneys the perfect dwelling. The common theory is that all bats carry the rabies virus which in actuality a very small percentage of bats carry rabies. Histoplasmosis is an airborne fungus that can grow in bat droppings (guano), but usually the guano must come into contact with moist soil which is normally not present in chimneys or dry attic environments. Bats can squeeze through openings 3/8" wide which is about the size of a dime. Exclusion is the number one priority in bat management. Exclusion of all holes larger than 1/4" is neccessary at all potential openings, and control should be left up to professionals.