The most common bats in Connecticut are the Little Brown Bat (about 3"long) and the Big Brown Bat (about 4"- 5"long), with the Little Brown being by far the most common. They are the only ones which are usually found in buildings. They can usually be found in attics, barns, sheds, old factory buildings, and abandoned buildings. They will always be found in the uppers areas of these buildings. They only need a space of 3/8" in order to gain entry. They are usually associated with a fairly large body of water (river, pond, lake, swamp, etc.) within a 1/2 mile or so. They usually leave in the fall to go hibernate in caves and old mines. Very rarely do they overwinter in their summer roosting areas, and if they do it is usually the Big Brown bat that does. No bat exclusion work should be done between June 1st and August 15th because of the presence of young flightless bats in the roost. Bats are extremely beneficial because of the number of insects they consume. One bat can consume 600 mosquitoes an hour. Any bat which swoops down at you at night is not attacking you, but is probably coming after the mosquito which is attracted to you. Bats can be rabies carriers and the current State protocol is to have any bat involved in human or domestic animal contact tested for Rabies. Contact includes waking and finding a bat in the room with you, or anyone else. Lately, a disease called 'White-nosed syndrome" has been killing off bats in the Northeast (it's estimated that 90% of the bats died in the last 7-8 years,. Bats reproduce very slowly, so it is going to be a long time before their population recovers, if it ever does. Please don't kill any bats, unless they must be tested for rabies.