The answer to 'what causes bed bug' is that bed bugs are small, flat insects that feed on human blood. They are typically found in the cracks and crevices of beds, furniture, and other areas where people sleep. Bed bugs are often brought into homes through infested luggage, furniture, or clothing, and can quickly spread throughout a home if left untreated.
Bed bugs are not a sign of dirtiness or poor hygiene, and they can infest even the cleanest of homes. They are primarily active at night and can be difficult to detect, as they are small and good at hiding. Signs of a bed bug infestation may include bite marks on the skin, blood spots on bedding, or the presence of the insects themselves.