Signs of bed bug infestation

Cathy Newkirk, Michigan State University Extension - November 21, 2012

Usually bites are the first sign of a bed bug infestation.

Usually bites are the first sign of a bed bug infestation (Purdue Extension Department of Entomology, “Bed Bug Bits and Bites”). Due to their small size and tendency to hide, bed bugs may be difficult to find. Michigan State University Extension has partnered with the Michigan Department of Community Health to address the bed bug issue.

Signs that bed bugs may be around include red, irritating bites, often in rows, typically on the neck, shoulders or arms (but there may be others reasons for these bites). The bites may also be accompanied by small blood smears on sheets or pillowcases. Clusters of dark spots may be found on the bed frame or edges of the mattress. The insects themselves might also be seen in the crevices, tufts and folds of mattresses and box springs, along with the light brown molted skins of the nymphs.

Bed bugs tend to hide during the day and come out at night. They will try to live as close to their food source as possible. They use heat and carbon dioxide sensors to find human hosts. They prefer to feed late at night or early in the morning when people are in their deepest sleep. Although the bed bug may feed for five to 15 minutes, it is rare to actually find them feeding. The bed bug’s saliva contains an anesthetic, so usually people will not feel or notice a bed bug biting them. Some people may not have any reaction to the bite, but most people will develop an itchy welt after being bitten. People who have severe bite reactions may be left with scarring.

After feeding, the bed bug leaves the host and retreats to its hiding spot where it digests its meal. During digestion it will defecate, leaving reddish brown spots. These spots are a common sign of an infestation. If the infestation is heavy, a sweet smell may be noticed in the room (Toronto Public Health, Bed Bugs).

For information on how to prevent or treat bed bug infestations, visit the Michigan Department of Community Health website, www.michigan.gov/bedbugs.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).