Diagnosis of an insect bite begins with a medical history and physical exam. Most of the time, diagnosis is clear because the person sees the insect when it bites. However, the red, raised area associated with a sting or a bite can appear much later without the person noticing the insect. These bites are much more difficult to diagnose since the type of insect is unknown. However, the size and location of the bite will give an indication of possible sources of the bite.