Answer to Case 395

Answer: Cimex lectularius, the common human bed bug. The other human bed bug is Cimex hemipterus, the tropical bed bug. While C. lectularius has a cosmopolitan distribution, C. hemipterus is found primarily in tropical regions. These 2 species can be differentiated by subtle morphologic features, which I won't get into here. As seen in this case, human bed bugs have a broad oval dorso-ventrally flattened body, short rudimentary front wings, and a laterally-flared pronotum lined with setae (hair-like structures).

Less commonly, bed bugs of birds and bats can also feed on humans. It is important to differentiate these from human bed bugs since the means of eradicating them from a home or office are usually different. You can tell the human bed bugs apart from bird and bat bed bugs by looking at the length of the setae compared to the width of the eye; the setae of the human bed bugs are shorter than the width of the eye, while the setae of bird/bat bed bugs is longer.

Here is a bat/bird bed bug for comparison. Note the prominent long setae.