What do Bedbug Bites Look Like? Bed bugs that infest human houses normally try to draw blood in the evening while the host is sleeping. Their bite is painless. However duplicated biting will result in small sores which are similar to the lesions arising from mosquito bites or flea bites. The sore is triggered by the body's response to the saliva that bed bug injects throughout the bite.They are flat and tiny and love to feed on blood.