Symptoms and Signs of Insect Bites and Stings

Medical Author:
Medically Reviewed on 11/10/2021

Doctor's Notes on Insect Bites and Stings

Insects are small animal arthropods that have six legs (hexapod invertebrates) and generally one or two pairs of wings. There are an estimated 10 million different insect species. However, the lay press equates insects with almost any small bug that bites or stings. Consequently, insect bites may be attributed to not only small arthropods but to other small invertebrate animals that can either bite, sting, or cause a chemical reaction (for example, blisters or pain) in human skin. Although some individuals would exclude stinging from biting insects, most medical and/or nonmedical individuals include stinging animals when discussing insect bites.

Examples of insect bites include mosquito bites, fire ant stings, bee stings, wasp stings, flea bites, chigger bites, tick bites, brown recluse spider bites, black widow spider bites, reduviid bug (also termed kissing bugs or Triatomine bugs) bites, puss caterpillar (skin reaction to released chemical skin irritant), and blister beetle (skin reaction to released chemical skin irritant).

If you can safely capture the insect or bug that likely bit or stung you, this may help your doctor to design the best treatment, if any, for you. However, if you develop any problems like tissue swelling or shortness of breath, go immediately to the emergency department.

The following are signs and symptoms of common insect bites:

  • Mosquito bites produce reddish raised, itchy lesions.
  • Fire ant stings produce blisters that are small and have pus in the center of the blister.
  • Bee stings with painful welt with possible mark in the center where the bee stung
  • Wasp stings are similar to bee sting.
  • Flea bites with small red bumps that itch, mainly on the legs and ankles
  • Chigger bites with small red lesions usually in warm areas like the waist, elbow, and knee folds
  • Tick bites after or during the initial bite; the initial bite site may be reddish
  • Brown recluse spider bites begin as reddish skin that can develop into a skin ulcer.
  • Black widow spider bites begin as two red puncture marks and can ulcerate.
  • Reduviid bug bites get contaminated with bug's feces; reddish-brown skin rash
  • Puss caterpillar (skin reaction to released chemical skin irritant); two to four rows of painful, reddish, small lesions that mimic the shape of the caterpillar
  • Blister beetle (skin reaction to released chemical skin irritant when bug is crushed): painful skin blisters, some lesions

Although most insect bite signs and symptoms usually only last a few days, many insects are vectors that may carry viruses, bacteria, and parasites that can harm humans or even kill them. Mosquitos can be vectors of several diseases that include malaria, yellow fever, West Nile, dengue, elephantiasis, and Zika virus. Depending on the type of tick, Lyme disease (signs and symptoms of reddish target lesions) or Rocky Mountain spotted fever (symptoms include small reddish rash) can be transmitted to humans. Reduviid bug bites can transmit the parasites that cause Chagas disease with symptoms and signs that include fever, eyelid swelling, headache, and splenomegaly. Stings from such insects as bees, wasps, and other flying insects that bite can cause allergic reactions that can be life-threatening such as swelling of the tongue or throat that can stop breathing if not treated emergently. Some skin lesions produced by insect bites may become infected. Brown recluse spider bites can result in local tissue destruction and crater-like scarring while the black widow spider bites can cause severe muscle cramping and central nervous system excitation due to the neurotropic toxin released in the bite.

What Are the Treatments for Insect Stings or Bites?

Treatments of insect bites and stings depend on the type of insect. However, there are general initial treatments that may be used for most stings and bites:

  • Safely remove the patient from the area to prevent additional stings, bites, or irritating agents.
  • Remove the stinger, biting insect, or irritating agents (like hairs from a caterpillar).
  • Wash the area with soap and water.
  • Apply a cold compress for at least 10 minutes.
  • Elevate the bite or sting area above your heart to reduce swelling.
  • Consider pain control with acetaminophen or ibuprofen. (Caution: Be aware of limitations of use in children.)

Call 911 if the person is allergic to certain bites and stings and develops more severe problems like difficulty breathing, swelling of face, or oral tissues, rapid heartbeat, can't swallow normally, or loss of consciousness. If an EpiPen is available, consider using it.

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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.