Flea bites and bed-bug bites look similar, but can be distinguished by their appearance and arrangement on the affected area. Flea bites appear in groups of three or four, whereas bed bug bites appear in a straight pattern of rows of three or more, according to MD-Health.com.
Flea bites appear as a small bump surrounded by a red skin rash, whereas bed bug bites look similar to mosquito bites, with a reddened raised area. WebMD states that scratching either of these types of bites can lead to an infection in the skin. MD-Health.com lists the most common locations of flea bites: ankles, armpits, waist, bends of knees and elbows. Bed bug bites are most commonly located on the neck, face, arms and hands. Although these are the most common locations, bites from either insect can appear anywhere on the body.