The appearance of an insect bite depends on the particular insect. For example, a mosquito bite creates a round, itchy pink or red bump on the skin. By contrast, a bed bug bite leaves a row of two or more red marks, notes Everyday Health.
The bite of the poisonous black widow spider leaves two puncture marks and causes muscle rigidity, pain and other symptoms, notes Everyday Health. The bite of the brown recluse spider, also poisonous, begins to look like a blister or bruise with a bluish purple area around it before crusting over and turning dark within eight hours.
Flea bites appear as a small group of three or four red bumps or as a rash characterized by swelling and hives a few hours after exposure, explains Everyday Health. The bite of an ant usually causes a red skin bump, although fire ant bites may cause the formation of fluid- or pus-filled blisters. Chigger bites cause itchy red welts with hardened skin surrounding the bite. This hardening results from the chigger’s injection of saliva, which liquefies the skin so that the chigger can consume it.