Bugs in the Attic

Updated November 21, 2016

Insect infestations are a common problem for many homeowners each year. While some insects are easy to spot, many others live in hidden areas of our homes such as attics and basements. Two insects often found in attics are bat bugs and cluster flies, which hide in protected places and come out only to feed.


Bat bugs bear a striking resemblance to bed bugs and often hide in attics where bats live. Like bed bugs, bat bugs are blood sucking insects that will bite humans if their bat host is not nearby. Bat bugs are small, oval-shaped insects that are reddish-brown in colour. After feeding, these insects are plump and dark red. Adult bat bugs can live up to one year without feeding, but female bat bugs must have blood to lay eggs. Cluster flies are another insect that often live in dark attics. These flies are large, black in colour and are usually seen swarming in window sills in the late fall to early spring. These flies received their name for their habit of clustering together in large numbers in attics, notes Iowa State University.


Bat bugs enter homes on the fur of bats, which often hide in attics. These insects are most plentiful on bats that roost in large colonies and on some species of birds. Bat bugs feed on their host, but come out to feed on humans if the bat leaves the attic. These insects usually come into homes through cracks in ceilings and feed on humans while they sleep. People bitten by bat bugs often develop colourless welts on their skin that itch which may last for over one week. Cluster flies hibernate in attics and swarm one or two times each year. These flies do not sting or bite humans but can become a nuisance for homeowners.

Cultural Control

Controlling bat bugs requires the removal of bats inside the home's attic. However, Ohio State University states that bats are non-game wildlife and cannot legally be killed. Consult your local wildlife office or pest control company for advice on how to eliminate bats living in your attic. Weatherproof your home and seal all cracks and crevices that may allow bat bugs easy entry. Repair or replace all window screens to keep birds and bats outside where they belong. Cluster flies are difficult to control, since the hibernate in well-protected areas such as the attic. Sealing all cracks underneath the eaves of your home, can help keep cluster flies from entering. Cluster flies tend to be more abundant after prolonged periods of wet weather during the summer months.

Chemical Control

Spraying your attic with insecticides can help reduce bat bug infestations. Treat areas such as around door frames, baseboards, electrical boxes and floors. Removing all dirt and debris from these areas before spraying insecticides can make treatments more effective. According to Ohio State University, it is important to avoid using highly repellent formulations, which can cause bugs to scatter about the home in different areas, making them more difficult to control. Cluster flies are often controlled by spraying insecticides on the outside of your home during the month of September. Cluster flies are almost impossible to eliminate when they are living in the protected area of an attic, making insecticides unnecessary.

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About the Author

Tracy Hodge has been a professional writer since 2007. She currently writes content for various websites, specializing in health and fitness. Hodge also does ghostwriting projects for books, as well as poetry pieces. She has studied nutrition extensively, especially bodybuilding diets and nutritional supplements.