Although my mother finds no bug in her Kona hotel bed, our fears are realized moments later when a white mark ringed in red rises on the top of her foot. Deep inside my mother's bug-induced bump swarms a beehive of chemical activity. If a spider's fangs are responsible, the toxic venom is flowing around the skin cells near the bite. Reacting as though the venom is a virus, her immune system bites back by producing antibodies. The antibodies and the venom proteins attach to the tissue cells around the bite, triggering the cells to release histamine.
Histamine is a powerful chemical that causes the cells to swell and itch.
Hence a bump. If someone is allergic, too much histamine can cause anaphylactic shock, a reaction characterized by difficulty breathing, dizziness, a drop in blood pressure, and even cardiac arrest. My mother's foot nipper was most likely a blood-sucking bug, so no venom was injected and her reaction to the bite will be no more than an itchy bump. The bite of a parasitic arthropod, which feeds on blood and includes the bedbug, mosquito, midge and black fly, triggers a histamine release, which produces the pale white bump surrounded by a reddish flare. The bump may itch, but the reaction usually disappears in a few hours as the irritant dissipates in the tissue and histamine levels fall.