Why do bedbug bites often appear in lines or clusters?

Bed bugs often feed in several quick attempts rather than one neat bite. As they move across exposed skin, they may probe and feed more than once, leaving a line or cluster of red marks. The pattern can vary depending on the person’s skin reaction and how long the insect feeds. These bites are not a reliable diagnosis by themselves, but the clustering is a common clue. Bed bugs are nocturnal and feed while hosts are asleep, which is why bites may be discovered only in the morning.